B-Type Eclipsing Binary Stars in the Bochum Galactic Disk Survey, C 2016 to My Parents and My Grandmother Maria

B-TYPEECLIPSINGBINARYSTARSIN THEBOCHUMGALACTICDISKSURVEY

DISSERTATION

zur Erlangung des Grades „Doktor der Naturwissenschaften“ an der Fakultät für Physik und Astronomie der Ruhr-Universität Bochum

von LENAMARIAKADERHANDT aus Herdecke

Bochum, 2016 gutachter: Prof. Dr. Rolf Chini, Ruhr-Universität Bochum PD Dr. Horst Fichtner, Ruhr-Universität Bochum

Disputation: 15.12.2016

Lena Maria Kaderhandt: B-type Eclipsing Binary Stars in the Bochum Galactic Disk Survey, c 2016 To my parents and my grandmother Maria

ABSTRACT

This thesis investigates eclipsing binary stars (EBs) of spectral type B in the Bochum Galactic Disk Survey (GDS). In order to place the B-type EBs in the context of other types of variable stars, both in terms of spectral and variability class, a general census of variable stars contained in the GDS was conducted first. By cross-matching the list of 64149 GDS variable sources with existing databases it was found that ∼90% of the catalogue matched stars were not known to be variable before. Of the known variable sources, 50.8% have not been classified yet, the others consist mostly of EBs (22.5%) and pulsating stars (22.8%). The variable stars with known spectral types are predominantly of type B (993 or 30.8%) and M (1001 or 31.1%). It was found that the majority of B stars with known variability type are EBs (229 or 23.1%) and that the fraction of EBs decreases to later spectral types. A brief survey of other variability types in spectral class B is also given. 237 B-type EBs – 167 known, 63 new and 7 of different catalogue classification – from the sample of automatically classified light curves provided by C. Fein were selected for further analysis. Amplitudes and lower limits for orbital eccentricities were calculated, yielding minimum eccentricities of up to ∼ 0.45. The new EBs were preliminarily grouped into contact classes, containing 16 contact (EC), 22 semi-detached (ESD) and 25 detached (ED) systems with periods from 0.32 d to 7.7 d in the EC, 0.7 d to 13 d in the ESD and 1.3 d to 25 d in the ED category. Flux amplitudes between 0.06 and 0.2 were found for the EC systems, indicating either low inclinations or their really being ellipsoidal variables. For half of the systems the brightness amplitudes are larger than 0.1 mag, which is in favour of their being EBs. Flux amplitude ratios are always close to 1. In the ESD and ED categories we find potentially larger inclinations, flux amplitudes reaching up to 0.4 and 0.3, respectively. The flux amplitude ratios imply significant temperature differences for many of the systems in both of these categories. Preliminary conclusions regarding the physical parameters of the new systems are provided along with suggestions for further studies. For the known EBs, catalogue periods were compared with our periods, finding agreement for the largest part. In one case we could improve on the catalogue period, in two more cases we provide a valid alternative where future measurements have to decide on the correct value.

PUBLICATIONS

Some results and ﬁgures have been published previously by the author in Kaderhandt et al. 2015:

Kaderhandt, L.; Barr Domínguez, A; Chini, R.; Hackstein, M.; Haas, M.; Pozo Nuñez, F.; Murphy, M: Variable stars in the Bochum Galactic Disk Survey. In: Astronomische Nachrichten, 336 (2015), September, S. 677. http://dx.doi.org/10.1002/asna.201512201. – DOI 10.1002/asna.201512201

vii

CONTENTS

1 INTRODUCTION 1 2 OBSERVATIONS AND DATA REDUCTION 5 3 VARIABLESTARSINTHEGDS-ANOVERVIEW 9 3.1 Source identification 9 3.2 Classification of variable stars 10 3.3 Spectral types and variability 12 3.4 Amplitudes 16 4 B S TA R S 19 4.1 Eclipsing binaries 34 4.1.1 New eclipsing binary candidates 49 4.1.2 EB candidates with different catalogue classification 69 4.1.3 Known eclipsing binaries 75 5 S U M M A RY A N D O U T L O O K 79 A A P P E N D I X A - TA B L E S 81 A.1 Amplitudes and eccentricities 81 A.2 Calculated spectral types 90 B APPENDIX B - CONCEPTS AND METHODS 95 B.1 Orbital elements 95 B.2 Newton’s method 97 B.3 Calculation of intrinsic star colours 98

B I B L I O G R A P H Y 101

ix LISTOFFIGURES

Figure 1 Magnitudes of GDS variables in r0 (blue) and i0 (red). 6 Figure 2 i0 versus r0 magnitudes of all GDS variables. 7 Figure 3 Distribution of the known variables over variability types. 11 Figure 4 Distribution of variable stars over spectral types. 12 Figure 5 Distribution of the main variability types over spectral types. 14 Figure 6 Left: i0 vs. r0 magnitudes of all stars with known spectral type, right: the same without classes M, S, C and N. 16 Figure 7 Amplitude distribution for all sources in r0 (blue) and i0 (red). 17 Figure 8 i0 vs. r0 amplitudes plotted separately for all known variables and for each category. Note that axis scales have been adapted for each category. 18 Figure 9 Distribution of the B stars over variability types. 19 Figure 10 Light curve of DW CMa, blue=r0, red=i0, black=nearby constant comparison star for each filter. 20 Figure 11 Light curve of V640 Car, colour scheme as in Figure 10. 21 Figure 12 r0 light curve of HD 90834 folded with P = 231 d. 22 Figure 13 Light curve of IRAS 07377-2523, colour scheme as in Figure 10. 23 Figure 14 Light curve of HU CMa, colour scheme as in Figure 10. 24 Figure 15 r0 light curve of TYC 8977-2816-1, folded with P = 3.40701 d. 26 Figure 16 r0 light curve of V426 Car, folded with P = 7.5375 d. 26 Figure 17 r0 light curve of V754 Mon, folded with P = 1.505 d. 27 Figure 18 r0 light curve of HD 65743, folded with P = 1.84372 d. 28 Figure 19 Light curve of V735 Car, folded with P = 3.145 d. Blue=r0, red=i0. 29 Figure 20 Light curve of HD 141926, colour scheme as in Figure 10. 30 Figure 21 Top: Light curve of HD 330950 in r0. Bottom: Light curve of HD 330950 in i0. Nearby constant comparison source in black. 31 Figure 22 Sloan filter curves. r0 is in red, i0 in purple. 32 Figure 23 Amplitudes of Be stars in i0 vs. r0. 33 Figure 24 Schematic EB configurations and corresponding typical light curves. 36

x List of Figures xi

Figure 25 Minima timing. 37 Figure 26 Eclipse geometry (based on Smith 1995). 38 Figure 27 Dependence of eccentricity on phase difference. 41 Figure 28 Top: Distribution of calculated mean minimum eccentricites with a bin size of 0.01, bottom: mean eccentricity vs. period with logarithmic period axis. 42 0 Figure 29 r light curve of BN Cir, P = 4.4098 d, emin = 0.45. 43 0 Figure 30 r light curve of V674 Car, P = 19.811 d, emin = 0.31. 44 0 Figure 31 r light curve of HD 306096, P = 5.38322 d, emin = 0.3. 45 Figure 32 Periods of the EB sample, bin size 0.5 d. 46 Figure 33 Colour-colour diagram for all 192 EBs where UBV measurements were available. The intrinsic colours of the main sequence are plotted in colour with violet=O, blue=B, cyan=A, green=F, yellow=G, orange=K, red=M. Also shown is an extinction vector

for spectral type B0 and a visual extinction of Av = 2 mag. 48 Figure 34 Period distribution for the EC (top), ESD (middle) and ED systems (bottom), bin size 0.5 d. 50 Figure 35 Minimum eccentricity versus period for the new EB candidates; black=EC, red=ESD, blue=ED. 51 Figure 36 Flux-normalised r0 light curve of CD-24 5898A, P = 7.66801 d. 52 Figure 37 Flux-normalised r0 light curve of HD 300814, P = 3.39773 d 53 Figure 38 Flux-normalised r0 light curve of CCDM J06493-0239AB, P = 1.33653 d. 54 Figure 39 Flux-normalised r0 light curve of TYC 4799-714-1, P = 6.32693 d. 55 Figure 40 Flux-normalised r0 light curve of TYC 8959-350-1, P = 5.38739 d. 56 Figure 41 Flux-normalised r0 light curve of 2MASS J06401339-0114484, P = 4.17805 d. 57 Figure 42 Flux-normalised r0 light curve of BD-17 5191s, P = 0.395328 d 57 Figure 43 Flux-normalised r0 light curve of HD 328533, P = 4.65906 d. 59 Figure 44 Flux-normalised i0 light curve of HD 150723, P = 4.70469 d. 60 Figure 45 Flux-normalised r0 light curve of CPD-59 2618, P = 0.97187 d. 62 Figure 46 Flux-normalised r0 light curve of [ICS99 A], P = 3.48027 d. 62 Figure 47 Flux-normalised r0 light curve of HD 168862, P = 4.44639 d. 64 Figure 48 Flux-normalised r0 light curve of HD 60366, P = 4.27526 d. 65 xii List of Figures

Figure 49 Flux-normalised r0 light curve of CPD-26 2634, P = 5.47088 d. 66 Figure 50 Flux-normalised r0 light curve of HD 53542, P = 2.38978 d. 67 Figure 51 Flux-normalised r0 light curve of HD 295887, P = 4.69846 d. 67 Figure 52 Flux-normalised r0 light curve of CD-59 5583, P = 8.70544 d. 69 Figure 53 Flux-normalised r0 light curve of HD 295557, P = 9.55283 d. 70 Figure 54 Flux-normalised r0 light curve of HD 150792, P = 4.2394 d. 71 Figure 55 Flux-normalised r0 light curve of CD-56 5767, P = 1.89107 d. 72 Figure 56 Flux-normalised r0 light curve of V 724 Car, P = 0.90339 d. 72 Figure 57 Flux-normalised r0 light curve of HD 292711, P = 5.53059 d. 74 Figure 58 Flux-normalised r0 light curve of HD 302532, P = 3.75807 d. 74 Figure 59 GDS periods versus VSX periods. 75 Figure 60 i0 light curves of V493 Sct, left: catalogue period P = 30.811 d, right: our period P = 14.3326 d 76 Figure 61 r0 light curves of V0778 Sgr, left: catalogue period P = 4.0576 d, right: our period P = 2.02882 d 77 Figure 62 r0 light curves of DT Pup, left: catalogue period P = 3.34342 d, right: our period P = 4.94246 d. 77 Figure 63 Light curve of HD 97726. Left r0, right i0. P = 74.64 d. 78 Figure 64 Ellipse parameters. F, F’=focal points, a=semi-major axis, b=semi- minor axis, e=eccentricity. 95 Figure 65 Orbit orientation with respect to reference plane. 96 Figure 66 True (ν) and eccentric (E) anomaly. C=centre, F=focal point, a=major axis, b=minor axis, e=eccentricity. 97 Figure 67 Illustration of Newton’s method. 98 Figure 68 Illustration of reddening. Squares=unreddened main sequence, dots=EB sample with UBV data, red lines=reddening paths. 99 LISTOFTABLES

Table 1 Variability of the identified stars 10 Table 2 Overview of known variables 12 Table 3 Distribution of variable stars over spectral types 13 Table 4 Variable stars sorted by spectral type 13 Table 5 High eccentricity EBs 46 Table 6 New EC candidates 58 Table 7 New ESD candidates 63 Table 8 New ED candidates 68 Table 9 New EB candidates 82 Table 10 EB candidates with different catalogue classification 84 Table 11 Known EBs 84 Table 12 Calculated spectral types for the new EB candidates 90 Table 13 Calculated spectral types for the EB candidates of different catalogue classification 91 Table 14 Calculated spectral types for the known EBs 92

xiii

1 INTRODUCTION

The study of stellar variability in its broadest sense may be said to reach back thousands of years, beginning with observations of novae and supernovae, which were bright enough to be noticed with the naked eye. The word "nova" means new, i.e. in former times it looked to naked-eye observers as if a new star had appeared in the heavens. Today we know that these extreme cases of stellar variability, far from mark- ing the birth of a new star, are due to outbursts in binary systems when gaseous material accreted by a compact star from its companion hits the former’s surface and triggers a thermonuclear runaway reaction (nova), which may even destroy the compact star in a supernova of type Ia if a certain mass limit is exceeded. Alternatively, a massive star may at the end of its "life" explode in a Type II supernova. With the ad- vent of improved scientiﬁc instruments, i.e. telescopes, cameras and spectrographs, it was discovered that there is actually a whole menagerie of variability in stars, reaching from small-scale variations of under 0.1 mag to over 10 mag, caused by a diverse range of physical processes, a selection of which we will encounter in this thesis. These are not only interesting phenomena in their own right, but may also provide us with useful tools for other purposes like distance measurements, as in the case of the classical Cepheids or Type Ia supernovae. In recent years, the study of photometric and spectroscopic variability in stars has also led to advancements in the understanding of stellar multiplicity, especially in the high-mass regime. In concise terms, photometrically, a star may turn out to actually consist of two or even more components when its light output is monitored closely over a continuous time span because the components eclipse each other by turns if the orbital plane is sufﬁciently aligned with the line of sight. The representatives of spectral type B of these so-called eclipsing binaries (EBs) are the main subject of this thesis. The photometric approach taken here may be supplemented by spectroscopic observations, which can show periodic changes in the radial velocity of the stars via shifting spectral lines. There is now growing evidence that most high-mass stars occur as binary or multiple systems, with important implications for theories on massive star formation, as laid down in Mason et al. 2009, Sana & Evans 2011 and Chini et al. 2012, among others. The

1 2 INTRODUCTION

spectroscopic survey of Galactic O- and B-type stars by Chini et al. 2012 in particular re- vealed that ∼80% of 249 southern O-type stars (O3.5-9) show radial velocity variations due to multiplicity; additionally, 540 B stars showed a decreasing multiplicity fraction from B0 (∼ 60%) to B9 (∼ 15%), which, however, might be an observational artefact introduced by the disappearance of He lines towards later spectral types. Studies of individual nearby and extragalactic open clusters imply multiplicity fractions ranging between ∼20% and ∼60% (Sana & Evans 2011 and references therein). Due to the unknown orbit inclination the spectroscopic method yields only lower limits on the stellar masses. Likewise, the detectable minimum mass of a potential secondary component is severely limited by the brightness contrast between the primary and the secondary spectrum. Therefore, complementary methods like photometry and advanced imaging techniques are desirable. The latter aim to astrometrically resolve suspected close binaries into their component stars using Speckle interferometry (Mason et al. 2009), lucky imaging (Maíz Apellániz 2010) or adaptive optics (Duchêne et al. 2001, Harayama et al. 2008). As for photometry, wide-ﬁeld multi-epoch imaging surveys offer a unique opportunity to detect variables among large samples of stars and yield their periods and brightness amplitudes. In particular, the discovery and classiﬁcation of binary stars has been steadily increasing in the last decade thanks to several long-term photometric programs like Hipparcos (Eyer & Grenon 1997), NSVS (Northern Sky Variability Sur- vey, Wo´zniaket al. 2004), ASAS (All Sky Automated Survey, Pojmanski 1997), APASS (AAVSO Photometric All-Sky Survey, Smith et al. 2010), KIC (Kepler Input Catalogue, Kepler Mission Team 2009) and the UKIDSS (Galactic Plane Survey, Lucas et al. 2008). The data for this thesis have been taken from The Bochum Galactic Disk Survey (GDS) as described by Haas et al. 2012, Hackstein et al. 2015 and Hackstein 2015. As described in Chapter 2, this ongoing photometric survey aims to obtain a comprehen- 0 0 ◦ sive census of variable stars with 8 . i , r . 181 in a stripe of ∆b = ± 3 around the southern Galactic plane. A study of the multiplicity among the most massive stars in the GDS, i.e. those of spectral type O, has already been conducted by A. Barr Domínguez (Barr Domínguez 2014, Barr Domínguez et al. 2013a, Barr Domínguez et al. 2013, Barr Domínguez et al. 2013b). The aim of this thesis was to investigate the much larger sample of B-type stars with emphasis on EBs. As laid down in Chapter 3, a general statistical analysis of the variable sources with regard to known variability and spectral types was conducted

1 The Sloan r (617 nm) and i (748 nm) ﬁlters. INTRODUCTION 3

first in order to place the B stars into a wider context and to provide an overview of what the GDS has to offer. EBs are objects of significant interest in their own right, not just for their contribu- tion to multiplicity studies. As explained in Chapter 4, analysis of their light curves may provide us with insight into the physical parameters of the component stars and their orbits, like temperature, stellar radii and orbital eccentricity. To this end I utilised the results obtained by C. Fein in the framework of his PhD thesis (Fein 2016). In an effort to automatise the detection and classification of EB candidates, he wrote a software which utilises machine learning. This software looks for periodicity in the light curves provided by the GDS and estimates the likelihood of them belonging to EBs based on feature extraction and an extremely randomised tree trained on a reference set. Taking the resulting EB candidates of spectral type B, I refined the selection by hand and analysed all light curves with respect to minima positions and amplitudes, the former were then used to derive lower limits for orbital eccentricities. These calculations helped to identify candidates where follow-up observations and theoretical modelling may provide yet deeper insight into their physical parameters – for example, in the case of eccentric systems, a rotation of the line of apses (precession of the orbit) may occur, which is dependent on the internal structures of the stars (see for example Claret & Gimenez 1993 and Claret 1997). Thus, such systems may present us with an observational test of the theory of stellar structure and evolution. Also of great interest are systems where mass exchange between the components takes place, which may affect the evolution of the components stars and trigger eruptions. About one quarter of the light curves I selected belong to stars which were not known as EBs before, thus illustrating the potential of the GDS for multiplicity studies. Finally, I also used UBV data from the GDS to obtain independent approximate spectral classifications of the EB systems, which in many cases resulted in earlier spectral types than those provided by existing databases. Since the UBV measurements have rather large errors as of yet, these results have to await confirmation by future improved measurements. This thesis is structured as follows: Chapter 2 gives an overview of the observational and data reduction methods as well as the data itself. Chapter 3 offers a statistical analysis of the variable sources contained in the GDS, after which Chapter 4 focusses on B stars in general and B-type EBs in particular. Finally, in Chapter 5 a summary of the results is presented along with the perspectives they offer for future research.

2 OBSERVATIONSANDDATAREDUCTION

The observations were carried out with the robotic 15 cm twin refractor RoBoTT of the Universitätssternwarte Bochum, located near Cerro Armazones in Chile1. The results presented here are based on the data release of May 2015, comprising almost five years worth of observations. They cover 1323 square degrees of the southern galactic disk in 268 fields of 2◦ × 2◦ each. Each field had at this point been observed up to 272 times in the Sloan r0 and i0 filters (effective central wavelengths 617 nm and 748 nm, respectively, see also Figure 22 in Chapter 4). One observation consists of a series of nine dithered images with 10 seconds exposure time each, which are combined during data reduction. Starting in 2014, observations in the Johnson U (360 nm), B (440 nm), V (540 nm) and Sloan z0 (893 nm) filters have been added. At the time of this writing, each field has been observed at least once in these filters; completion is expected within 2016. The main purpose of extending the filter set is to determine classical colours (like B-V and U-B) in order to obtain a rough spectral energy distribution, which will allow us to estimate important parameters like temperatures, visual extinction and infrared excess. As will be seen in 4, I have already taken advantage of these new data in order to calculate approximate spectral types. Sources were checked for variability using three different methods: the standard deviation of the light curves, the amplitude and Stetson’s variability J-Index. For details on this and the data reduction process, the reader is referred to Haas et al. 2012, Hack- stein et al. 2015 and Hackstein 2015. Variable sources are assigned confidence flags based on the detection method (i.e. variability is detected in two filters or detected in both, but exceeding variability threshold in only one, or is detected in only one filter) and the quality of the photometric measurements as well as the stability of the source’s lightcurve.

1 http://www.astro.ruhr-uni-bochum.de/Astrophysik/all_infos.html

5 6 OBSERVATIONSANDDATAREDUCTION

Figure 1: Magnitudes of GDS variables in r0 (blue) and i0 (red).

The sensitivity of the survey is illustrated in Figure 1, where the distribution of magnitudes in the r0 and i0 ﬁlters is plotted for all GDS variables using 0.5 mag bins. Although this histogram contains only variable stars it is representative for the sensitivity of the entire GDS. Obviously the useful brightness range starts at r0, i0 ∼ 8 mag; brighter stars tend to saturate and were thus omitted from the analysis. The faint end of the GDS is at around r0 ∼ 18 mag and i0 ∼ 16 mag and thus roughly coincides with the saturation limit of the Large Synoptic Survey Telescope (LSST)2, r0 ∼ 16. In this sense the GDS provides a complementary survey for the brighter Galactic sources the LSST project does not reach. Altogether more objects have been measured in i0 (60676) than in r0 (56267), which is mainly due to the fact that at the start of the survey observations were only conducted in i0.

2 http://www.lsst.org/lsst/ OBSERVATIONS AND DATA REDUCTION 7

Figure 2: i0 versus r0 magnitudes of all GDS variables.

In Figure 2 i0 versus r0 magnitudes are plotted for the complete sample. Two features immediately hit the eye - ﬁrst, the vast majority of sources is brighter in i0 than in r0. In concrete terms, 52794 sources have measurements in both ﬁlters, out of these, 50465 (95.6%) are brighter in i0 than in r0, in contrast to 2128 (4.03%) sources which are brighter in r0 than in i0 and 201 (0.381%) sources for which r0 = i0. The preponderance of sources with i0 < r0 is mainly a result of extinction caused by interstellar dust. The mean magnitude difference for the whole sample is r0 − i0 = 1.30 mag. The second striking feature is that the distribution is bimodal. This is an effect of spectral class, as will be shown in the next chapter.

3 VARIABLESTARSINTHEGDS-AN OVERVIEW

3.1SOURCEIDENTIFICATION

To identify the variable sources and determine which of them are new discoveries in terms of variability, I matched the source list of 64149 entries first with the SIMBAD1 database as well as the 2MASS2 catalogue and finally with the VSX3 using a 10" search radius each. This radius was a compromise between the varying positional accuracies of the databases on one hand and to minimise the probability of multiple matches on the other. The matchings were performed using Topcat4, an interactive graphical user interface for manipulating and cross-matching astronomical data tables. The SIMBAD cross-match yielded identifications for 16053 (∼25%) of the sources, most of the remaining ones had matches in the 2MASS catalogue, leaving 506 sources unidentified, amounting to ∼0.8%. Taking a closer look at these reveals that 331 or 66% are flagged as C with regard to the photometry, i.e. lowest confidence, so they might be spurious detections. In the following, sources identified in SIMBAD will be referred to as SIMBAD sources and those only identified in 2MASS as 2MASS sources. As the reduction process is being continually refined, some objects with currently low confidence might be eliminated from future updated compilations. On the other hand, with more observations being added continuously, providing both a longer time basis and a larger field coverage, new variables might be found. Therefore, the numbers given here will continue to be revised; it is reasonable to assume, however, that the general trends and conclusions presented in this thesis are unlikely to change significantly. To ascertain how many and which of the identified sources are already known to be variable, I cross-matched them with the VSX and found 4747 of the SIMBAD- and 2099 of the 2MASS-sources listed as variable therein. A further 482 and 52, respectively,

1 http://simbad.u-strasbg.fr/simbad/ 2 Two Micron All Sky Survey, http://www.ipac.caltech.edu/2mass/ 3 International Variable Star Index, https://www.aavso.org/vsx/ 4 http://www.star.bris.ac.uk/∼ mbt/topcat/

9 10 VARIABLESTARSINTHEGDS-ANOVERVIEW

are listed as suspected of variability and altogether 7 are marked as constant or non- existent. However, there is also a total of 102 sources which are variable according to SIMBAD yet are not contained in the VSX and 50 non-stellar sources, which are of no interest to this study. Table 1 summarises these ﬁndings, leaving out the non- stellar sources. A total of 1322 of the VSX-identiﬁed sources were in fact put into the catalogue in 2012 by our own team, based on an earlier release of the GDS, so in the following they will be counted as new. Thus, subtracting all constant sources, those already known or suspected of variability, and the non-stellar sources, this leaves 57929 (∼90% of the complete sample) potentially new variable stars.

Table 1: Variability of the identiﬁed stars

SIMBAD 2MASS

total 16053 47590 variable 4849 2099 suspected 482 52 constant 6 1

3.2CLASSIFICATIONOFVARIABLESTARS

In this thesis the classiﬁcation of variable stars will follow the scheme employed in the VSX, which recognises six categories deﬁned by the mechanisms causing the brightness variations:

• Eclipses: Double/multiple systems whose orbital planes coincide with our line of sight, leading to eclipses when one star moves in front of the other.

• Rotation: Brightness variations caused by spots moving in and out of sight due to rotation of the star itself, ellipsoidal shape or heating in a double/multiple system, leading to variations in brightness as the emitting area the observer sees changes in the course of a revolution.

• Pulsation: Contraction and expansion of the outer stellar layers leading to changes in temperature and surface area, which affect the brightness. Amplitudes of ∼ 0.1 − 9 mag, periods of ∼ 0.5 − 1000 d. 3.2 classification of variable stars 11

• Eruption: Mass ejections or chromospheric activity causing erratic changes in brightness.

• Cataclysmic events (novae): Binary systems where at least one component is a white dwarf, which accretes material from its companion leading to brightness outbursts when material hits the surface or when enough material has accumu- lated to trigger a thermonuclear runaway reaction. Amplitudes can be as high as 20 magnitudes, the so-called dwarf novae are periodic with P ∼ 10 − 1000 d.

• X-ray: Binary systems where one component is a neutron star or black hole, accreting matter from the other component. Due to the strong gravitational forces involved, the accretion process leads to intermittent emission of X-rays. The brightness variations may also be seen in the optical part of the spectrum. Am- plitudes up to 9 mag.

Table 2 provides an overview of the known variable stars in both the SIMBAD and the 2MASS sample, where "Unknown" refers to unknown variability type. While about half belong in the latter category as of yet, the other half is almost entirely made up of pulsating and eclipsing stars in almost equal proportion. Figure 3 illustrates this graphically. The subsequent analysis will focus on the SIMBAD sources only, as 2MASS does not provide spectral types.

Figure 3: Distribution of the known variables over variability types. 12 VARIABLESTARSINTHEGDS-ANOVERVIEW

Table 2: Overview of known variables

Pulsating EB Erupting Rotating Cataclysmic X-ray Unknown

SIMBAD 1377 1196 126 103 22 3 2021 2MASS 209 364 1 9 6 0 1511

Total 1586 1560 127 112 28 3 3532 Percentage 22.8% 22.5% 1.83% 1.61% 0.403% 0.0432% 50.8%

3.3SPECTRALTYPESANDVARIABILITY

Spectral types are given for 3224 (20%) of all stars identiﬁed with SIMBAD. Figure 4 and Table 3 display the overall abundance of spectral types regardless of known variability. One notices that by far most of the stars with known spectral type are of spectral types B and M, each accounting for about 30%. For the M stars, one could argue that they are the most numerous class in the Galaxy and, containing several variable types, will thus naturally contribute a large part to the variable sample. This argument would not hold true, however, for the B stars, which, as massive and (by implication) short-lived stars are comparatively rare objects, so the fact that our sample of variables contains so many of them points to intrinsically high variability among this group.

Figure 4: Distribution of variable stars over spectral types. 3.3 spectral types and variability 13

Table 3: Distribution of variable stars over spectral types

O OB B A F G K M S W N,C,R 59 85 993 303 129 105 106 1001 218 29 196 1.83% 2.64% 30.8% 9.4% 4% 3.29% 3.29% 31.1% 6.76% 0.9% 6.08%

The relationship between spectral and variability type is explored in Table 4. SIM- BAD lists stars for which the spectral type is undecided between O and B as OB, which has been adapted as its own category here. Also, spectral types N, C and R were put into one category as all three are varieties of the larger group of carbon stars. It turned out that of the 3224 stars with known spectral type, 1668 or 52 % are already known to be variable or at least suspected. In Table 4, "unknown" means stars known to be variable but without further classiﬁcation and "new" are those newly discovered by the GDS. The table and Figure 5 clearly demonstrate the prevalence of M-type pulsating stars and also point to a major part of the reason behind the high percentage of variable B stars - their intrinsically high multiplicity fraction: Most of the variable B stars of known variability type in our sample are EBs. Also notable is the number of O/OB EBs, which is higher here than in any other variability category. After the B stars, there is a consistent decline in the number of EBs towards later spectral types, as can be seen most strikingly in Figure 5.

Table 4: Variable stars sorted by spectral type

O OB B A F G K M S W N,C,R ∑

pulsating 0 4 21 6 43 21 9 290 47 0 68 508 EB 9 11 229 117 37 27 12 1 0 2 0 445 erupting 2 2 64 5 3 1 2 4 0 11 3 97 rotating 3 0 20 21 3 13 30 6 0 0 0 96 cataclysmic 0 0 0 0 1 1 0 7 0 1 0 10 X-ray 1 0 2 0 0 0 0 0 0 0 0 3 unknown 8 7 62 14 6 6 18 189 58 0 59 427 suspected 4 4 33 1 0 0 0 27 7 2 3 81 new 32 57 562 139 36 36 35 477 106 13 63 1556

∑ 59 85 993 303 129 105 106 1001 218 29 196 3224 14 VARIABLESTARSINTHEGDS-ANOVERVIEW

Figure 5: Distribution of the main variability types over spectral types. 3.3 spectral types and variability 15

These findings are consistent with the results from previous multiplicity studies, as summarised by Duchêne & Kraus 2013, which suggest that multiplicity increases with mass. On a cautionary note, however, one must also consider that the likelihood of observing an eclipse increases with the size of the component stars - obviously, it is more likely that an eclipse can be observed if the components are large, and O and B stars are among the largest stars in the Galaxy. From the percentage of known EBs in the early spectral types it can be projected that hundreds of new massive EBs may be contained in the GDS archive. Looking at Figure 5, other features which immediately hit the eye are the pronounced majority of B stars in the eruptive category, the high number of K stars among the rotating variables and especially the predominance of M stars among the cataclysmic stars. The nature of cataclysmic variables suggests that the M stars in this latter group are in fact just one component of a binary system, where the other one would be a white dwarf accreting mass from the (probably evolved) M star – and in fact, all seven M stars in this category are classed as Z Andromedae (ZAND) variables, symbiotic systems known to consist of a hot star and a late-type star whose envelope is excited by the hot star’s radiation which causes irregular brightness variations of up to 4 mag in V. We do indeed find such large amplitudes in our data, in one case even 6 mag in r0 and 4.63 mag in i0. One of the ZAND variables is also marked as OH/IR in SIMBAD, i.e. an asymptotic giant branch star which is very bright in the near-infrared and additionally shows strong OH maser emission as a result of strong stellar winds. Checking the brightness of this object, I found that it is indeed almost three magnitudes brighter in the i0 than in the r0 filter (i0 = 9.77 ± 0.01 mag, r0 = 12.62 ± 0.01 mag). The eruptive B stars will be treated in some detail in chapter 4 in the context of emission line stars. The rotating variables are the only group to feature prominently among the K stars; the majority of these are not classified further. However, there are four instances of RS Canum Venaticorum variables, which are noteworthy because they are known to be binary systems and display several interesting photometric and spectroscopic features indicating hightened chromospheric activity and prominent star spots. These would certainly be interesting candidates for a future study. Coming back to the bimodal distribution in Figure 2 of Chapter 2, if one plots all stars with known spectral type, the result is as shown in the left diagram of Figure 6. Making the plot separately for each spectral class reveals the origin of the distribution – the lower "clump" is comprised mainly of spectral class M and the parallel classes 16 VARIABLESTARSINTHEGDS-ANOVERVIEW

S, C and N, which contain late-type giant stars displaying chemical peculiarities in their spectra. These classes were left out in the right diagram in Figure 6, which clearly eliminates the lower part of the distribution. Thus, for stars of unknown spectral type, simply plotting i0 versus r0 magnitudes could give us a ﬁrst estimate of whether they are likely to be of these later types.

Figure 6: Left: i0 vs. r0 magnitudes of all stars with known spectral type, right: the same without classes M, S, C and N.

3.4AMPLITUDES

Figure 7 displays the distribution of brightness amplitudes for all our variable sources with 0.2 mag bins.5 As already mentioned, there are not always measurements in both filters; additionally, there are cases in which the difference between the measurements in both filters is larger than the bin size used here, both factors contributing to the differences between the histograms for each filter. Of the two outliers with amplitudes larger than 7 mag, one is the nova Cen 2012, the other is an infrared source which has not been studied further as of yet. Plotting i0 vs. r0 amplitudes separately for the main variability categories as in Figure 8 reveals that the otherwise largest amplitudes belong mainly to the pulsating stars, which is in agreement with expectations. In the diagram for the cataclysmic stars, one notices one object with a much larger amplitude in i0 than in r0 in the upper left. This is another nova, Sct 2009. We also see that the majority of known variables in our survey have amplitudes that are larger in r0 than in i0. The most marked differences occur again for the pulsating stars and the difference becomes more pronounced for larger amplitudes. A check for pulsators with r0 amplitudes larger than 2 mag and more than 0.5 mag amplitude difference between r0 and i0 reveals that these

5 Amplitude here means the difference between largest and lowest measured brightness over the entire time span covered. 3.4 amplitudes 17

Figure 7: Amplitude distribution for all sources in r0 (blue) and i0 (red). are mostly Mira-type variables which are indeed known to show larger amplitudes in the visual than the infrared and generally large amplitudes of 2.5 to 11 mag in V6. For the other groups there is no such clear trend, although the EBs show a slight tendency to larger r0 amplitudes for larger overall amplitudes (of course, the other groups are also much smaller, the cataclysmic and the X-ray variable sample being too small for statistic assessment). Here, the systems with large amplitude differences in favour of r0 are exclusively those classified as semi-detached systems of the Algol-type, where one star is usually significantly smaller and hotter than the other. Error bars were omitted from these diagrams for reasons of clarity, but the errors are below 0.02 mag for the vast majority of sources. Coming back to Figure 7, the number of stars declines toward larger amplitudes, as one would expect, with 81% of the amplitudes in r0 and 77% of the amplitudes in i0 being less than or equal to 1 mag. Medium (∼ 3 − 4 mag) amplitudes are found in the cataclysmic, eruptive and also the pulsating category as well as for a few EBs. Almost all rotating variables display only very small amplitudes . 0.4 mag, while for most EBs amplitudes are larger than this, but smaller than 1 mag. This might serve as a first criterion for deciding whether a source is more likely to be an EB than a rotating variable. The three X-ray variables, not shown here, have amplitudes of less than one magnitude.

6 The Johnson V band partly overlaps with the Sloan r0 band, but hardly with Sloan i0. 18 VARIABLESTARSINTHEGDS-ANOVERVIEW

Figure 8: i0 vs. r0 amplitudes plotted separately for all known variables and for each category. Note that axis scales have been adapted for each category. 4 BSTARS

As has already been stated, B and M stars form by far the most numerous groups of variable stars in the GDS. For those B stars with variability classiﬁcation, Figure 9 shows a graphic representation of their distribution over the variability categories. The marked prevalence of EBs, especially when compared to the other spectral classes, has already been discussed in the previous chapter. As to the other variability categories, the distribution of concise variability types within these is consistent with expectations.

Figure 9: Distribution of the B stars over variability types.

ERUPTIVEBVARIABLES

The second largest group, the erupting B stars, contains mostly Be stars, which will be discussed in more detail in the next section. The remaining eight objects in this group comprise four S Doradus variables, one FS CMa star, one Herbig Ae/Be star (see explanations below), one irregular variable and lastly, one double periodic variable, which is a binary containing an ellipsoidal star. The largest amplitude of 0.68 mag in

19 20 B S TA R S

r0 and 0.57 mag in i0 belongs to the Herbig Ae/Be star DW CMa. Herbig Ae/Be stars are basically the more massive pendant to T Tauri stars; they are deﬁned as pre-main sequence stars of spectral types B or A which are still embedded in gas-dust envelopes, display Balmer emission lines and are sometimes accompanied by circumstellar disks. Their variability is believed to be due to clumps in these disks, which is of particular interest, as these clumps may represent early stages of planet formation. In the case of DW CMa, we see erratic ﬂuctuations in brightness by as much as about half a magnitude on the timescale of tens of days, compare Figure 10. Its mean magnitude is smaller by 0.73 mag in i0 than in r0 which is consistent with the object being surrounded by circumstellar dust.

Figure 10: Light curve of DW CMa, blue=r0, red=i0, black=nearby constant comparison star for each ﬁlter.

In all of the plots for non-periodic sources I have always included near-constant comparison sources of similar brightness in the vicinity of the target star, to show that the sometimes quite small ﬂuctuations are intrinsic to the discussed star. I have also omitted error bars in these diagrams, as on these scales they would hardly have been visible in any case – they are on the scale of 0.01 to 0.02 mag. The next largest amplitude of 0.56 mag in r0 and 0.64 mag in i0 belongs to V640 Car, one of the S Doradus variables. These are high-luminosity Bpec-Fpec1 stars showing

1 "pec" is for peculiar. B S TA R S 21 irregular (sometimes cyclic) light changes with amplitudes in the range 1-7 mag in V. They are usually connected with diffuse nebulae and surrounded by expanding envelopes. Their behaviour is assumed to be an aspect of the Luminous Blue Variable (LBV) phenomenon, consisting of photospheric pulsations with time scales of hundreds to thousands of days. They also display micro-variations, stochastic variability and eruptions.2 The variability we were able to observe in our SDOR variables represents these latter categories. For V640 Car, we see ﬂuctuations of up to about 0.2 mag on time scales of tens of days. There does seem to be a long-term variability over the entire length of our observations (almost 1400 days) which might by cyclic, but this can only be decided by continued monitoring.

Figure 11: Light curve of V640 Car, colour scheme as in Figure 10.

HR Car shows a similar behaviour, albeit with smaller short-time variations of about 0.1 mag and an overall smaller amplitude of 0.25 mag, while for AG Car the brightness stays almost constant with small variations of up to 0.1 mag. For both stars only i0 data are available. V432 Car behaves similar to AG Car, with a decline in brightness of about 0.1 mag over the last 500 days covered by our observations. All four S Dor variables appear to be part of the η Carinae complex and with magnitudes between 7 and 9 mag they are among the brightest sources in our survey.

2 Adapted from the VSX website, https://www.aavso.org/vsx/index.php?view=about.vartypes 22 B S TA R S

The double periodic variable (DPV) HD 90834 is a supposed semi-detached inter- acting binary with a maximum amplitude of 0.39 mag in i0 and 0.37 mag in r0. The variability of such systems is composed of the orbital component, corresponding to time scales of several days, and a longer photometric cycle lasting about 33 times the orbital period3. In the present case, the orbital period is given as 6.8150 d in the VSX and the superperiod as 231 d. It is indeed possible to fold our data with this latter period, however I was unable to extract the orbital period. Figure 12 shows the r0 light curve folded with the superperiod.

Figure 12: r0 light curve of HD 90834 folded with P = 231 d.

The FS CMa variable IRAS 07377-2523 shows a maximum amplitude of 0.28 mag in i0 and 0.23 mag in r0. This type of variable is similar to classical Be stars in that it also exhibits hydrogen emission lines, but much stronger. Additionally, there are several forbidden lines in their spectra which are indicators of compact dust envelopes. They are thought to be binary systems undergoing rapid mass exchange, their light curves showing irregular long-term variations with mean magnitude changes of up to 2 mag in V.4 In the present case, one can see short-term variations on the scale of up to about 0.1 mag over the course of tens of days and an overall decline in brightness by 0.28

3 Adapted from https://www.aavso.org/vsx/index.php?view=about.vartypes. 4 Adapted from https://www.aavso.org/vsx/index.php?view=about.vartypes. B S TA R S 23 mag (the maximum amplitude given above) over the last 400 days of the recorded light curve.

Figure 13: Light curve of IRAS 07377-2523, colour scheme as in Figure 10.

Finally, the irregular variable HU CMa displays a maximum amplitude of 0.21 mag in i0 and 0.15 mag in r0. As the classiﬁcation suggests, the object displays erratic variations in brightness of up to about 0.1 mag over tens of days, see Figure 14. Interest- ingly, in SIMBAD the object is listed as a Herbig Ae/Be star5, however, the object is not markedly brighter in i0 than in r0 as one would expect from this type of star (for this reason r0 and i0 are shown separately in Figure 14), in fact, it is slightly brighter in r0, with i0 − r0 = 0.04. To gain more insight into the nature of HU CMa, spectroscopic observations would be needed.

5 Based on the 1999 paper A photometric catalog of Herbig Ae/Be stars and discussion of the nature and cause of the variations of UX Orionis stars by Herbst and Shevchenko. 24 B S TA R S

Figure 14: Light curve of HU CMa, colour scheme as in Figure 10. B S TA R S 25

PULSATINGBVARIABLES

The most numerous (16 out of 21) type of pulsating B stars are the β Cephei variables, stars of spectral type B0-B2 III-V showing short-period (0.1 to 0.3 d) brightness changes on the order of 0.01 to 0.3 magnitudes. For all of these, periods were already provided by the VSX. In most cases, we can confirm these periods, however, for V1207 Sco, folding the light curve with the VSX period of 0.28392 d does not even result in a recognisably periodic curve. The only folding which yields a periodic curve6 is with a period of 0.99638 d – and here almost all data points are concentrated along one flank of the curve. This, of course, does not represent a good fit and points to the possibility that this object indeed has a period very close to one day, which would result in most data points being collected around the same phase, because observations take place once a night and usually at around the same time. However, if this is so, the period is too long for a β Cephei variable. The five pulsating B stars which do not belong to the Beta Cephei category are four slowly pulsating B stars (SPB) and one PV Tel I star. SPBs usually have periods between 0.4 and 5 days and amplitudes less than 0.1 magnitudes. For our SPBs, periods are provided by the VSX, they range between 1.7 and 3.4 d, but agree only partially with our data. For TYC 8977-2816-1, the VSX states a period of 3.4108 d. I find the slightly different period of P = 3.40701 d, which, however does not visibly alter the quality of the fit. Shown in Figure 15 is the folding with P = 3.40701 d. For V536 Car the VSX lists a period of 1.45325 d, which does not yield any pattern whatsoever when used to fold our light curves of this star. Interestingly, SIMBAD lists this object as a β Cephei variable, however, neither in the corresponding period range nor in the SPB range do we find a periodicity (nor in any other range, for that matter), but we only have 36 data points in r0 and 33 in i0. PV Tel I variables are a subtype of the PV Tel variability – low-amplitude quasi- periodic light variations due to radial pulsations on a time-scale of 5 to 30 days. The underlying objects are hydrogen-deficient A or late-B supergiants.7 For the PV Tel I variable in our sample, V426 Car, no period is provided; our data can be folded with a period of 7.5375 d, although with a lot of scattering, see Figure 16.

6 For period determination I used the Laﬂer-Kinman method (Laﬂer & Kinman 1965). 7 Adapted from https://www.aavso.org/vsx/index.php?view=about.vartypes 26 B S TA R S

Figure 15: r0 light curve of TYC 8977-2816-1, folded with P = 3.40701 d.

Figure 16: r0 light curve of V426 Car, folded with P = 7.5375 d. B S TA R S 27

ROTATINGBVARIABLES

The group of rotating B variables consists mostly (14 out of 20) of α2 Canum Venati- corum stars, which are generally the most prominent group of rotating variables. It is thought that there is an inhomogeneous distribution of metals in the atmospheres of these stars, causing the brightness to vary across the stellar surface, so that we see the stars’ brightness changing as it rotates. The variations are typically on a scale of 0.01 to 0.1 mag over a period of 0.5 to 160 days and the stars are main-sequence stars of spectral type B8p-A7p8. The VSX provides periods for all ACV stars in our sample, except for one. The light curve of this star, V754 Mon, is best folded with a period of 1.505 d, for which it presents a very interesting picture: There are two maxima of different height and both of them are also slightly asymmetric. If the brightness variations are indeed due to the distribution of metals in the stellar atmosphere, the maxima might correspond to parts of the atmosphere where the metal density is smaller, as metals increase the opacity.

Figure 17: r0 light curve of V754 Mon, folded with P = 1.505 d.

8 p is generally for chemically peculiar, in the case of A stars it relates speciﬁcally to metals (in the usual chemical deﬁnition). 28 B S TA R S

For the other ACV, we can conﬁrm the VSX periods; there is another interesting case, HD 65743, which shows a behaviour similar to that of V754 Mon, see Figure 18. Its period is 1.84372 d. For both stars, the maximum amplitude is about 0.1 mag. Another curious feature is displayed in the light curve of V735 Car – here, one sees a very well deﬁned, symmetric maximum with an amplitude of about 0.15 mag. In between the maxima there is a slight rise in brightness, averaging to about 0.01 - 0.02 mag, and in the r0 curve, which has more than twice as many data points (106) as the i0 curve (51), one sees a brief peak at the same position of about 0.05 mag (see Figure 19).

Figure 18: r0 light curve of HD 65743, folded with P = 1.84372 d.

The remaining six rotating B variables are ellipsoidal variables, including the interesting high mass X-ray binary BP Cru, which is known to consist of an X-ray pulsar with a pulse frequency of 698 s orbiting around an ellipsoidal B2 supergiant on an eccentric orbit in 41.59 days. The system shows strong X-ray ﬂares which are caused by accreted material from the supergiant’s wind falling onto the pulsar, especially around the periastron. With our data it is currently not possible to verify the orbital period. I also checked for optical counterparts to the X-ray ﬂares, but within the time span covered by our data (1453.9 d or 3.98 years) there are none. However, it must be kept in mind that due to the changing visibility of the source over the course of a year, this time span is not covered continuously. B S TA R S 29

Figure 19: Light curve of V735 Car, folded with P = 3.145 d. Blue=r0, red=i0.

For the other ellipsoidal variables, periods are also provided by the VSX, they agree well with our light curves. Two of them, HD 150792 and HD 302532 are among the objects identiﬁed as EB by Fein’s classiﬁer and will be discussed in detail in subsection 4.1.2.

X-RAYBINARIES

Lastly, for the two high mass X-ray binaries (HMXBs) in the sample, V572 Pup and HD 141926, the VSX lists periods of 81.3 d and 9.4103 d, respectively. Our own data provide no confirmation of these and neither could I find other periods to fit the light curves. However, we do not have many data points for these objects yet (31 and 32 in the r0 filter, 29 and 28 in i0, respectively) and these are distributed over 1624.7 d (4.45 years) and 1172.8 d (3.21 years). Figure 20) shows the light curve of HD 141926. This system would certainly be worth closer monitoring, as it appears to be a triple system, containing the HMXB and a poorly studied irregular variable of spectral type B2e, according to the VSX. 30 B S TA R S

Figure 20: Light curve of HD 141926, colour scheme as in Figure 10.

V572 Pup ﬁrst shows a slow decrease in brightness of about 0.15 over a time span of 400 d and then brightens by almost 0.4 mag over about the same length of time, however, there are no data in between.

EMISSION-LINESTARS

In the most general sense, an emission-line star is a star whose spectrum shows emission lines, this is commonly denoted with an "e" in the spectral classiﬁcation. In the case of B stars, emission lines are usually due to circumstellar material which has been ejected in the form of stellar winds and eruptions, they may also be produced by discs of material formed in the course of mass transfer between the components of a binary system. 150 of our B stars are marked as general emission-line stars in SIMBAD. Sepa- rate from these, there is a special kind of B-type emission-line star, the Be stars, which are deﬁned as non-supergiant B stars exhibiting emission in one or more Balmer lines. This phenomenon is thought to be caused by a gaseous disk of material ejected from the star due to rapid rotation. B S TA R S 31

Of the 64 known eruptive B-type variables in our sample, 56 are Be stars. The majority (36) of the latter are designated Gamma Cassiopeiae stars, named after the prototype of Be stars, which was discovered to show emission in Hβ in 1867 by Father Angelo Secchi.

Figure 21: Top: Light curve of HD 330950 in r0. Bottom: Light curve of HD 330950 in i0. Nearby constant comparison source in black. 32 B S TA R S

Today they are defined as rapidly rotating O9-A0 III-Ve stars with mass outflow from their equatorial zones, thus brightening irregularly by up to 1.5 mag in V. While there are no such dramatic brightness changes in our sample, we do find eruptions of up to about 0.6 mag occurring over a time span of tens of days, as in the case of HD 330950, see Figure 21. Apart from this, one can see several smaller flare-ups in brightness on the order of 0.1-0.2 mag. In addition to the B stars listed as Be in the VSX, there are 80 more in SIMBAD. These are, for the most part, only entered as "VAR" or "MISC" in the VSX as of yet and some as "suspected of variability", four have not been included in the VSX at all so far. Five of the 80 systems have been entered in different categories in the VSX, among them the above mentioned HMXB HD 141926 (the third component appears to be a Be star), one double-periodic ellipsoidal variable (HD 90834, discussed in the previous section) and three EBs, one containing a giant or supergiant component and one being a contact system. One might surmise that the variability of the Be stars is dominated by fluctuations in their Hα emission. In that case, one would expect their amplitudes to be larger in the r0 than in the i0 filter. Figure 22 shows representative transmission curves for the Sloan filters; Hα corresponds to a wavelength of 656.3 nm.

Figure 22: Sloan ﬁlter curves. r0 is in red, i0 in purple.9

9 https://www.aip.de/en/research/facilities/stella/instruments/data/sloanugriz-ﬁlter-curves B S TA R S 33

As Figure 23 shows, if anything, there is a trend in the opposite direction, with amplitudes tending to be larger in i0 than in r0. In numbers, for 69 stars the i0 amplitude is larger than the r0 amplitude, compared to 40 stars with a larger amplitude in r0 and 7 stars with equal amplitudes in r0 and i0 (for 20 stars measurements are not available in both ﬁlters). Taking the errors into consideration, most sources may on average have the same amplitude in both ﬁlters.

Figure 23: Amplitudes of Be stars in i0 vs. r0.

The largest overall amplitude (0.75 mag in r0, 0.51 mag in i0) belongs to HD 97726, which is the above-mentioned EB system containing a giant star. Here, the amplitude is due to the eclipses, not due to eruptions, as folding the light curve with the VSX period of 74.64 clearly shows (more on this system in subsection 4.1.3). The two next largest amplitudes belong to GCAS stars, both with larger i0 than r0 amplitudes. The ﬁrst one is the already mentioned HD 330950 and here, the difference between the r0 and i0 ﬁlter is due to there being fewer measurements in the former, especially around the peak in brightness, compare Figure 21. For the next system, HD 152291, the amplitude difference appears to be genuine. Generally, the discrepancy in data points in r0 and i0 cannot be used to explain the prevalence of larger i0 amplitudes, as the majority of the sources in fact has more measurements in r0 than i0. That being said, on the basis 34 B S TA R S

of our data we cannot draw a deﬁnite conclusion on the nature of the variability in Be stars at this point.

4.1ECLIPSINGBINARIES

The main goal of this work was to investigate the EB population among the B stars in the GDS, especially to find and analyse new candidates. To this end, I used the results obtained by C. Fein in the framework of his thesis (Fein 2016) to which the reader is referred for details on the detection and classification algorithms. All in all, I got 456 B stars preliminarily identified as EBs by Fein’s classifier, among them all of the 229 B-type EBs mentioned in Chapter 3 except for one. The latter is Cl* Westerlund 1 W 13, a contact system in the open cluster Westerlund 1, which has been extensively studied by Koumpia & Bonanos 2012. Using both spectroscopic and photometric data, they found a period of 9.2665±0.0003 d, which I was unable to verify on the basis of our data. However, with an average 14.83 mag in r0 (we do not have an i0 light curve yet), the object is relatively weak and there is a lot of scattering in our light curve, which may be partly due to the very crowded environment of this star. Of the 228 stars which are not among the already known EBs, 202 are new discoveries by the GDS and a further 14 have entries in the VSX as other kinds of variables, consisting of seven eruptive stars, five rotating variables and two pulsating stars. Six are designated as miscellaneous or unknown type and a further six are suspected of variability. Although the overall success rate of the classifier is high, as the almost complete detection of already known EBs shows, like any other automated light curve classifier it is not perfect. Thus, by visual inspection, I sorted out 219 of all 456 light curves due to obvious misidentification as EB (in the case of new candidates or those with different catalogue classification), or because of bad quality of the light curve (for example due to unfavourable sampling). I still included a number of light curves with comparatively few data points, in some cases less than 30, if they looked reasonably auspicious. These should be regarded more as promising candidates for follow-up observations than certain EB discoveries. I have included the number of data points for each light curve in the tables in Appendix A, which may serve as a guideline for the confidence grade of the light curves. Of the 237 remaining stars, 167 belong to those already known as EBs. Those known EBs that did not make it into the selection do have a recognisable EB shape but are not of sufficient quality for the subsequent analysis that is explained below. Of the other 4.1 eclipsing binaries 35

70 candidates, 63 are new variable discoveries by the GDS, the remaining 7 stars are known variables with different catalogue classifications. It should be added that the classifier was designed to find periods up to 40 days. For longer periods the detection probability decreases because the folding algorithm operates in frequency space – longer periods translate to lower frequency resolution, which introduces a bias towards shorter periods (as will be seen shortly, most EBs in this sample have periods under ten days). In some cases, however, EBs with longer periods may be detected because the classifier erroneously finds a shorter period, which still makes it look sufficiently like an EB to be automatically classified as such. In the sample discussed below, there is one of these cases - an EB detected with a period of 0.670942 d, which in truth has a period of 74.64 d (discussed in more detail in Section 4.1.3).

PRINCIPLESOFLIGHTCURVEANALYSIS

Fundamentally, EB systems may be divided into three types, based on the extent to which the components fill their respective Roche lobes10: detached, semi-detached and contact systems. In detached systems, each of the component stars sits well inside its Roche lobe, whereas in a semi-detached system, one of the components fills its Roche lobe and therefore, mass may be transferred to the other component. Finally, in contact systems, both components fill or even overfill their Roche lobes, thereby creating a common envelope around the stellar cores. Figure 24 illustrates these different cases graphically, together with typical corresponding light curves. From the light curves it is in principle possible to make inferences about the temperatures and radii of the stars. First, the relative depths of the minima depend on the temperature ratio of the stars. Assuming two stars at a distance d from Earth, with

radii R1 and R2, where R1 > R2, and surface flux densities F1 and F2, the total received flux is given by 1 S = R2F + R2F (1) tot d2 1 1 2 2 For a perfect edge-on orientation of the orbit relative to our line of sight, i.e. an inclination of 90◦, the flux received during the eclipse of star 2 is simply R 2 S = 1 F (2) 1 d 1 During the eclipse of star 1, the flux is given by 1 R 2 h R2 F i = 2 − 2 + 2 = 1 − 2 − 2 S2 2 R1F1 R2F1 R2F2 F1 1 2 1 (3) d d R1 F1 10 The Roche surface is the critical equipotential surface around the stars in a binary system which inter-

sects itself at the so-called L1 Lagrange point. As shown in Figure 24, it is of a ﬁgure-eight shape with one of the stars at the centre of each lobe. 36 B S TA R S

Figure 24: Schematic EB conﬁgurations and corresponding typical light curves.11

Therefore, the ﬂux ratio is given by S R2 F 2 = − 2 − 2 1 2 1 (4) S1 R1 F1

The surface flux density is connected to the temperature via the Stefan-Boltzmann law 4 F = σSBT , so for the temperature ratio we obtain s S R2 T 4 T R 2 S 2 = − 2 − 2 ⇒ 2 = 4 − 1 − 2 1 2 1 1 1 (5) S1 R1 T1 T1 R2 S1 Obviously, if the stars have the same radius, this relation allows the direct calculation of the temperature ratio from the measured flux amplitude ratio – in this case equation 5 reduces to s T S 2 = 4 2 (6) T1 S1 For an edge-on configuration, if the stars have the same radius, this is seen in the shape of pointed minima, while for different radii one would see minima with a plateau at the bottom. In this case the ratio R1 can also be obtained from the EB light curve, as R2 illustrated in Figure 25. Assuming a constant orbital velocity (i.e. circular orbit), from

11 Light curves: http://www.vs-compas.belastro.net/bulletin/issue/2/p6 4.1 eclipsing binaries 37

Figure 25: Minima timing.12

Figure 25 we can see that the radius of star 2 is given approximately13 by v + v R = 1 2 t − t (7) 2 2 b a

where v1,2 are the corresponding velocities of the stars. The radius of star 1 is v + v R = 1 2 t − t (8) 1 2 c a Therefore, for a circular orbit the radius ratio is simply given by

R t − t 2 = b a (9) R1 tc − ta If the spectral type and luminosity class of one of the stars is known, its temperature and radius are fixed and for the ideal case presented above it is thus in principle possible to calculate the corresponding quantities of the second star. However, in general, the physical reality will not be so ideal. In the first instance, the orbit will often not be oriented exactly along the line of sight, i.e. i < 90◦, which results in the stars not completely eclipsing each other so that the corresponding dips in the light curve will be less deep and sharp, thereby mimicking at first glance the shape of a light curve belonging to a system of equal-size components even if they are not. Looking at the amplitude in flux instead of magnitude may help to judge this – if the eclipse is only partial, the dips in flux will naturally be more shallow than they would be for a total

12 http://www.astro.sunysb.edu/metchev/PHY521/lecture26.pdf 13 This assumes motion along a straight line in the given time interval. 38 B S TA R S

eclipse. But without computational modelling to match the observed light curve, trying different combinations of inclinations and temperature ratios etc. it is hard to arrive at deﬁnite conclusions regarding the physical parameters of such systems. The condition for an eclipse to occur at all is

a · cos(i) ≤ R1 + R2 (10)

where a is the distance between the stars’ centres, as illustrated in Figure 26.

Figure 26: Eclipse geometry (based on Smith 1995).

A further, lesser complication may arise from orbital eccentricity, since the orbital velocities of the stars may then not be assumed to be constant.

CALCULATIONOFAMPLITUDESANDECCENTRICITIES

Although computational modelling was unfortunately beyond the time frame of this thesis, I still performed preliminary calculations which may serve as starting points for future modelling efforts and help to give a first insight into the natures of the systems examined here. To this end I determined the phase positions of the minima, which served to calculate lower limits for the orbital eccentricities, see below. I also calculated the depths of the eclipses both in magnitudes and in normalised flux and the corresponding ratios. In order to do all this, it was first necessary to determine 4.1 eclipsing binaries 39

the combined brightness for each system relative to which amplitudes could then be calculated. To this end, I wrote a routine which takes the five brightest points from each light curve and determines their median value, which is then taken as the combined brightness; the corresponding error is calculated from the median absolute deviation (MAD) plus the error of the data point which represents the median. This method of determining the combined brightness was chosen firstly, because obviously, for contact binary light curves, which are sinusoidal in shape, simply taking the mean or median of all data points would result in the combined brightness being determined as lying about halfway between minimum and maximum; secondly, for detached systems with a clear plateau between the minima, taking the median instead of the mean of the five lowest magnitudes will eliminate outliers. The choice of five data points was a compromise to suit a wide range of light curves with varying coverage, for detached systems with well-sampled plateaus between the minima this will generally slightly overestimate the combined brightness. Having established this, the routine then takes the approximate locations of the minima provided by user input and, in an interval of five measurements to the left and to the right of the data point closest to the user’s estimate, looks for the largest magnitude which is then used to calculate the amplitude of the minimum, the error consisting of the data point’s error plus the error of the combined brightness.14 In some cases, where the light curve was sinusoidal in shape and sparsely covered so that less then or exactly five data points separated the minima, I narrowed the search range to three datapoints in each direction of the estimated position. Fluxes were calculated using the zero magnitude flux for the corresponding filters and then using the relation between flux and magnitude,

S2 = 100.4(m1−m2) (11) S1

setting S1 as the zero magnitude flux and correspondingly m1 = 0. The flux was then normalised to the flux corresponding to the combined brightness so that the normalised flux is 1 when both components are visible. It should be noted here that in most cases there is not an equal amount of data points in both filters and sometimes this may lead to the depth of a minimum being underestimated in one filter because measurements are lacking. One prominent example will be shown in subsection 4.1.3. As mentioned above, I also made an approximate, lower-limit determination of the systems’ eccentricities using the phase separation between the minima. In the case of a perfectly circular orbit, the time interval between primary and secondary minimum is exactly half the period, i.e. the phase difference is 0.5. If the orbit is elliptical, the orbital

14 The sample does not contain systems with marked plateau minima, so there usually is one lowest point in the light curve. 40 B S TA R S

velocity of the stars is not constant and the time interval from primary to secondary is only equal to the time interval from secondary to primary minimum if the major axes of the orbits are aligned with the line of sight. In the following we will assume that the line of sight is parallel to the minor axes of the orbits, in which case the effect described above is maximal, thus yielding a lower limit for the true eccentricity. Under this assumption the phase difference between the minima, D, is connected to the eccentricity e via Kepler’s equation in the following manner15:

E0 − e sinE0 = π(1 − D) (12)

Here, E0 is the eccentric anomaly at the time of one of the minima; it is one of three angular parameters ("anomalies") which can be used to describe the position of a body on its orbit (see Appendix B for a more detailed description). For the assumed orientation

of the orbits’ minor axes, E0 itself is connected to the orbital eccentricity via

cosE0 = e (13) √ Using this and sin(arccos(x)) = 1 − x2, we can write equation 12 as follows: p arccos(e) − e 1 − e2 = π(1 − D) (14)

Obviously, this equation can not be solved analytically for e, so I used Newton’s method (see Appendix B) to solve it numerically. Figure 27 shows how the eccentricity thus calculated corresponds to the phase difference – obviously, the eccentricity changes almost linearly with the phase difference; in fact, in the interval from D = 0.2 to D = 0.5 the curve is very well approximated by the linear equation e = −1.63954 D + 0.819770. Thus, in this range, if one miscalculates D by 0.01 this results in a difference of 0.0164 in e. All of the systems in our sample fall into this linear range. Detailed results for all of the 237 selected EBs are given in Tables 9 to 11 in Ap- pendix A. In the cases where there is a marked difference between the eccentricity calculated in one ﬁlter versus the other, there is usually strong scattering around the minimum position or a signiﬁcant difference in coverage. The difference usually amounts to much less than 0.1. For the following diagrams I calculated eccentricites from the means of the phase differences measured in r0 and i0.

15 See standard texts on EBs, for example Kallrath & Milone 2009. 4.1 eclipsing binaries 41

Figure 27: Dependence of eccentricity on phase difference.

Figure 28 shows a histogram of the calculated lower-limit eccentricities with a bin size of 0.01 and a plot of eccentricity vs. the corresponding period. The vast majority of the systems have e < 0.1, with only 14 displaying a lower-limit eccentricity larger than or equal to 0.1. The lower diagram shows that almost all of these have periods in the interval from P = 2 d to P = 8 d; there is a slight trend towards longer periods for higher eccentricities. For tight systems, dynamical friction will tend to circularise the orbits.16 However, estimates as to the typical time scale on which this happens vary widely; at this point it is not possible to say if the eccentricity of a tight early-type binary system is due to a disturbance or capture of one of the components at some point in its history or because it is simply too young for circularisation to have taken effect – B-type stars have main-sequence lifespans of only 10 to 100 million years (for comparison, the sun, a G2V star, has a main-sequence lifespan of around 9 billion years and M stars at the low-mass end of the spectral sequence "live" for over a trillion years). Three of the stars with e ≥ 0.1 are located inside open clusters, most notably CPD- 59 2618, a prospective semi-detached EB – one of our discoveries – with a minimum eccentricity of e = 0.168 and very short period of 0.971896 d; it is part of Trumpler

16 For large-scale studies of binary stars concerning this phenomenon, compare for example Duquennoy & Mayor 1991 and Latham et al. 2002. 42 B S TA R S

Figure 28: Top: Distribution of calculated mean minimum eccentricites with a bin size of 0.01, bottom: mean eccentricity vs. period with logarithmic period axis.

16, a massive open cluster containing some of the most luminous stars of the Milky Way, itself part of the very large Carina OB1 association located within the Carina Nebula. The system must be quite young, SIMBAD listing its combined spectral type 4.1 eclipsing binaries 43 as B1.5V, while our UBV measurements (see below) even indicate B0.5. Together with its being part of densely populated area of space this makes it feasible that the systems’ eccentricity is due to interactions with other systems or because the system was created by tidal capture. For the candidate contact binary CD-59 5281, the system with the shortest period of 0.31797 d and a minimum eccentricity of 0.089, no such case can be made. SIMBAD lists simply B for its spectral type, while our data point to B1, which would make it a young system, so perhaps there has not been sufﬁcient time for orbit circularisation. The record holder in the current sample is BN Cir with a lower-limit eccentricity of e = 0.45. This is one of the already known EBs with a period of 4.4098 d. Our data are in very good accord with the corresponding VSX entry, which contains a remark as to its high (but heretofore not calculated) eccentricity, listing the phase difference from primary to secondary minimum as 0.78, the same as our value, and a visual magnitude of 10.5 in the secondary minimum. We ﬁnd r0 = 10.487 ± 0.026 mag, i0 = 10.691 ± 0.021 mag in the secondary minimum. Figure 29 shows the light curve in r0, which is better sampled than the i0 light curve.

0 Figure 29: r light curve of BN Cir, P = 4.4098 d, emin = 0.45.

The spectral type given in SIMBAD is B9III/IV, our data indicate B2.5. With comparatively large and sharp ﬂux amplitudes of about 0.23 and 0.28 the inclination is 44 B S TA R S

probably quite large, too and the components of slightly different temperatures. This system would certainly be a good candidate for modelling. The candidate with the next largest minimum eccentricity of 0.31, V674 Car, is also an established EB, in this case an Algol-type detached system with a comparatively long period of 19.811 d. Again, our data agree very well with the published values; a remark in the VSX lists the phase distance from primary to secondary minimum as 0.29 and a visual magnitude of 10.24 mag in the secondary minimum, my calculations yield 0.3 and r0 = 10.356 ± 0.026 mag, i0 = 10.460 ± 0.022 mag. The VSX remark postulates faint companions, which unfortunately cannot be ascertained on the basis of our data (yet). The spectral type is given as B8, whereas our data indicate a much earlier B0. As in the previous case, the large and slightly different ﬂux amplitudes imply a large inclination and slightly different temperatures - another promising modelling candidate. Figure 30 shows the r0 light curve.

0 Figure 30: r light curve of V674 Car, P = 19.811 d, emin = 0.31.

The third largest minimum eccentricity of 0.3 belongs to another known detached EB, HD 306096, with a period of P = 5.38322 d and spectral type B0V. In this case our UBV data agree with the spectral type. Again, there is a remark concerning the high eccentricity in the VSX which places the phase difference from primary to secondary minimum at 0.68 – our value – and the secondary minimum’s visual magnitude at 9.42. For our filters, I find r0 = 9.353 ± 0.023, i0 = 9.368 ± 0.020 in the minimum. Figure 31 4.1 eclipsing binaries 45 shows the flux-normalised light curve in r0. In this case, there is a very clear difference in the amplitudes, implying an equally significant difference in the temperatures of the component stars. The r0 light curve is displayed in Figure 31.

0 Figure 31: r light curve of HD 306096, P = 5.38322 d, emin = 0.3.

Table 5 lists all EBs with e ≥ 0.2, where m2 is the brightness in the secondary minimum, Fs/Fp is the flux amplitude ratio of the minima and D1 is the mean phase distance from primary to secondary minimum. The last column shows whether the system is a known EB or not. More data can be found in the Tables in Appendix A. For the other known EBs in this list, the agreement with the catalogue data is again very good, the remaining new EBs will be discussed in subsection 4.1.1. Figure 32 gives an overview of the periods for all EBs in our sample with 0.5 day bins, where the four systems with P > 20 d have been omitted for reasons of clarity. The preponderance of short-period systems is evident at first glance - 67% have periods shorter than four days, with a marked peak in the range between around one and two days, which contains 28% of the sample. From an observational point of view, the high fraction of short-period EBs conforms with expectations – shorter periods mean tighter systems and the closer the stars, the likelier they are to be observed eclipsing each other. There is also a bias towards shorter periods inherent in the algorithm used for folding the light curves; it operates in frequency space and the frequency resolution is lower for larger periods, which are therefore harder to find. 46 B S TA R S

Table 5: High eccentricity EBs

Name Spectral type Period/d m2/mag Fs/Fp D1 emin known? SIMBAD GDS Period r0 i0 r0 i0

BN Cir B9III/IV B2.5 4.4098 10.487 ± 0.026 10.591 ± 0.021 0.839 ± 0.140 0.79 ± 0.102 0.777 0.45 yes

V674 Car B8 B0 19.811 10.356 ± 0.026 10.460 ± 0.022 0.962 ± 0.149 0.983 ± 0.127 0.303 0.315 yes

HD 306096 B0V B0 5.38322 9.353 ± 0.023 9.368 ± 0.020 0.475 ± 0.149 0.418 ± 0.132 0.688 0.3 yes

HD 168862 B3II B0 4.44639 9.496 ± 0.021 9.376 ± 0.018 0.728 ± 0.152 0.691 ± 0.141 0.666 0.264 no

HD 312051 B – 7.92908 11.287 ± 0.025 11.175 ± 0.028 0.516 ± 0.109 0.841 ± 0.150 0.663 0.259 yes

V346 Cen B2II/III – 6.32166 8.761 ± 0.043 8.930 ± 0.025 0.805 ± 0.420 0.714 ± 0.225 0.657 0.233 yes

HD 60366 B9III B3.5 4.27526 10.192 ± 0.025 10.277 ± 0.016 0.936 ± 0.278 0.885 ± 0.172 0.369 0.207 no

CPD-26 2634 B9III B6 5.47088 11.424 ± 0.021 11.545 ± 0.022 0.484 ± 0.073 0.687 ± 0.113 0.628 0.202 no

The longest period found in our sample is 74.64 days, it belongs to HD 97726, which is one of the already known EBs – it is listed in the VSX as an Algol-type EB containing at least one giant/supergiant component. This is the object mentioned earlier which was only detected by the classiﬁer because it found a much shorter period of 0.670942 d. We will return to this object in subsection 4.1.3.

Figure 32: Periods of the EB sample, bin size 0.5 d. 4.1 eclipsing binaries 47

SPECTRALTYPES

I used the newly acquired UBV measurements of the GDS in an effort to approximately determine spectral types, in addition to those provided by SIMBAD, which are often without subclass and/or flagged as being of low quality (see Appendix B for details on the method I employed). Of course, it has to be kept in mind that the spectral types thus determined will usually be composites of the spectral types of the component stars, just like most of the spectral types given in SIMBAD. I assumed the stars to be dwarfs, which is not unreasonable, as any star will spend the largest part of its life on the main sequence, but will of course not be true in all cases. Measurements in all three filters were available for 192 of the 237 EBs treated here. In principle, measurements have been taken for all GDS fields, however, some sources are either too weak or too bright for our instruments in these filters. It turns out that the spectral types implied by our data are almost always earlier than those found in SIMBAD. With about a third of the systems being of earlier types than B5 even according to SIMBAD, one of the components might actually be of spectral type O, but to determine this with certainty, spectroscopic observations would be needed. In fact, for 13 stars my calculations already point to spectral type O. Although none of these appear to be part of an open cluster or an OB association, they are among the stars with the highest visual extinction in the sample. This indicates their being located in very dusty regions of the Galaxy, which strengthens the case for them really being of type O. On the other hand, the errors inherent in the UBV measurements range from ∼ 0.06 mag to ∼ 0.3 mag in (B − V) and even up to ∼ 0.5 mag in (U − B) for the potential O stars, which would be sufficient to place the candidates among the B-type stars. Thus, a definite conclusion cannot be drawn at this point. For the entire sample, errors are in the range of ∼ 0.04 mag to ∼ 0.83 mag in (B − V) and ∼ 0.06 to ∼ 0.81 mag in (U − B)17, which introduces an uncertainty of at least one subclass for most of the OB range. Precise measurements and errors may be looked up in Tables 12 to 14 in Appendix A along with the calculated spectral types. Figure 33 shows the colour-colour diagram for all 192 EBs for which UBV data were available. The intrinsic colours were taken from Fitzgerald 1970.

17 For a single case, the known EB AC Sct, the (U − B) error is 2.17 mag. 48 B S TA R S

Figure 33: Colour-colour diagram for all 192 EBs where UBV measurements were available. The intrinsic colours of the main sequence are plotted in colour with violet=O, blue=B, cyan=A, green=F, yellow=G, orange=K, red=M. Also shown is an extinction vector

for spectral type B0 and a visual extinction of Av = 2 mag. 4.1 eclipsing binaries 49

4.1.1NEWECLIPSINGBINARYCANDIDATES

As mentioned at the beginning of this section, there are a total of 63 new EBs in the current sample. Based on the shapes of their light curves I grouped them – independently of the preliminary classification provided bei Fein – according to probable contact class, i.e. detached (ED), semi-detached (ESD) and contact (EC). This grouping should only be seen as preliminary, as sometimes the dividing line between EC and ESD or ESD and ED is not that obvious and modelling would be needed to make a more definite decision. ED systems typically have well defined plateaus between the minima, but for close systems the distinction between ED and ESD can become difficult on the basis of the light curve alone. As for EC and ESD systems, the former have a common envelope and will therefore tend to have similar temperatures, i.e. similar minima depths. Thus, for two systems without clear plateaus between the minima, if one has decidedly different minima depths, it is more likely to be a semi-detached system than a contact system. The majority are prospective detached systems, 25 in total, followed by 22 semi- detached and 16 contact systems. Periods range from 0.32 days to 24.8 days, where those below one day belong to EC and ESD systems and the longest periods are found among the ED and ESD systems, in line with expectations. Figure 34 shows the corresponding period distributions plotted with a bin size of 0.5 d. Minimum eccentricities range from zero to 0.26; from Figure 35 it can be gathered that the highest eccentricities occur for the ED systems, as one might expect, with the ECs consistently showing minimum eccentricities . 0.1. The ESDs fall mostly into this range, too. 50 B S TA R S

Figure 34: Period distribution for the EC (top), ESD (middle) and ED systems (bottom), bin size 0.5 d. 4.1 eclipsing binaries 51

Figure 35: Minimum eccentricity versus period for the new EB candidates; black=EC, red=ESD, blue=ED.

In the following subsections I will present cases of special interest, data on all systems can be found in the accompanying tables and the tables in Appendix A. The former list ﬂux amplitudes, brightness amplitudes may be looked up in the latter. The light curve shown will normally be the one with more measurements, unless otherwise stated. For the majority of these new systems, references in the literature are scarce, most are only listed as part of a survey.

PROSPECTIVEECSYSTEMS

For all potential EC systems it is striking that the flux amplitudes are quite small, none surpassing 20%, which is indicative of these systems having either comparatively low inclinations or maybe not being EBs at all but ellipsoidal variables. As mentioned briefly in Chapter 3, these are close binary systems with gravitationally deformed components in which the changes in brightness are due to different aspects of the emitting areas towards us in the course of a revolution but without eclipses. They usually show brightness amplitudes below 1 mag, whereas for half of our sample, the amplitude is larger than 1 mag in at least one minimum. In either case, however, our findings would imply the discovery of new binary systems. The flux amplitude ratios are always close 52 B S TA R S

to one (the lowest belonging to TYC 4799-714-1 with 0.696 in r0 and 0.644 in i0, see below), implying similar temperatures for the components. Starting with the EC candidate with the longest period of P = 7.66801 d, CD-24 5898A is the primary component of a known visual double star listed in the Washing- ton Visual Double Star Catalog (WDS). According to this listing, the components are separated by 10.7”, which virtually precludes the possibility of its being a true binary star. The visual magnitude of the primary is given as 9.52 mag, we measure a combined brightness of 9.67 ± 0.012 mag in r0 and 9.905 ± 0.007 mag in i0. The spectral type, according to the WDS, is B9, our own UBV data point to a spectral type of B4. With ﬂux amplitudes of about 5-6%, the system must either have a comparatively low inclination or it might be an ellipsoidal variable. The small primary brightness ampli-

Figure 36: Flux-normalised r0 light curve of CD-24 5898A, P = 7.66801 d.

tude of 0.072 ± 0.021 in r0 and 0.055 ± 0.014 in i0 (differences are due to the different number of measurements) are in favour of the latter. Spectroscopic observations of this object would be highly desirable in order to look for periodic radial velocity changes and possibly obtain more precise physical parameters of the would-be components. The r0 light curve is shown in Figure 36. A similar case with entries in both the WDS and the Catalog of Components of Double & Multiple stars (CCDM) is HD 300814. It is listed as the primary component of a double star with a visual magnitude of 9.43 mag and 9.2 mag, respectively (we 4.1 eclipsing binaries 53 measure a combined brightness of 9.132 ± 0.012 mag in r0 and 9.076 ± 0.009 mag in i0), whereas the secondary component has a visual magnitude of 11.3 mag and an angular distance of 1.9” to the primary, according to the newest measurement (1976) listed in the WDS. For a distance of 1534 pc, as reported by Kaltcheva & Scorcio 2010 for the primary component, this would place the secondary 0.01413 pc or 2914.5 AU apart from the primary, if the system were a physical double star, i.e. a binary, which is uncertain at this point. However, the system is also a member of the compact cluster candidate Lodén 112, an environment which is not favourable to binaries with such large separa- tions. In any event, our light curve of the primary indicates that this may indeed be a

Figure 37: Flux-normalised r0 light curve of HD 300814, P = 3.39773 d binary star where the components orbit each other in 3.39773 days. The spectral type, according to SIMBAD, is B3, our UBV data indicate B0. The ﬂux amplitude of around 7% again implies a rather low inclination or that the system is an ellipsoidal variable, however, the brightness amplitude is around 0.1 mag, which puts it rather at the limit for the latter. Figure 37 shows the r0 light curve. There is yet another system which has an entry in both the WDS and the CCDM, this is CCDM J06493-0239AB, listed as a B9IV/V system by SIMBAD and A0 in the WDS, where it is not clear, however, if this is a composite spectral type for both components or for one. They have a very similar brightness - 10.26 mag and 10.91 mag in V according to the WDS and are separated by one arcsecond – unfortunately, we cannot resolve 54 B S TA R S

this pair, so both our measured brightness, 9.751 ± 0.009 mag in r0 and 9.843 ± 0.008 mag in i0, and our calculated spectral type of B5 are to be seen as composite values for the known components. Since both components have the same proper motion (-2 mas/yr in RA, 2 mas/yr in Dec), it is reasonable to assume that this is a true binary. The light curve suggests that the system contains either an EB or an ellipsoidal variable, compare Figure 38, which would make this either a triple system or show that the known components actually eclipse each other. As only two measurements are reported in the CCDM and three in the WDS, between 1940 and 1991, it seems entirely possible that this has been missed up to now, especially as the brightness amplitude is less than 0.1 mag.

Figure 38: Flux-normalised r0 light curve of CCDM J06493-0239AB, P = 1.33653 d.

As mentioned at the beginning of this section, the lowest ﬂux ratio in the EC sample of about 0.6 to 0.7 belongs to TYC 4799-714-1, which also has the second-longest period, see Figure 39. In this case our spectral type agrees with the one provided by SIMBAD, B2. The luminosity class is given as IV, i.e. subgiant, so the system appears to contain at least one developed component. The primary ﬂux amplitude is still quite low, around 10%, so if this is an EB, the system’s inclination is probably rather low, too. The brightness amplitude in the primary minimum is just above 1 mag, thus putting it slightly in favour of EB over ellipsoidal variable. 4.1 eclipsing binaries 55

TYC 8959-350-1, the system with the third-longest period of 5.38739 d, shows a sharp drop about halfway down both its minima (only seen in one minimum in the i0 ﬁlter, but that is quite obviously due to missing data points compared to r0), which could be due to extended envelopes around the stars so that the eclipses start with the envelope of one star moving in front of the other before its core eclipses the other star’s core. But without modelling, this is only speculation. The system also has one of the larger ﬂux and brightness amplitudes, ∼ 0.12 and ∼ 0.14 mag in the primary minimum, respectively, thus making it one of the best candidates among the prospective ECs for a true EB. According to SIMBAD, the spectral type is B2, unfortunately, the GDS lacks the requisite UBV data in this case. The r0 light curve is shown in Figure 40.

Figure 39: Flux-normalised r0 light curve of TYC 4799-714-1, P = 6.32693 d.

The highest flux amplitude of 0.141 ± 0.031 in r0 and 0.187 ± 0.050 in i018 in the primary minimum belongs to 2MASS J06401339-0114484, as shown in Figure 41. The corresponding brightness amplitude is 0.166 ± 0.03 and 0.225 ± 0.05, respectively, which is in favour of EB over ellipsoidal variable. Here we also see a well-defined difference between the depth of the minima with a flux amplitude ratio of about 0.8. SIMBAD

18 The light curves are almost equally well sampled (138 vs. 110 measurements, respectively), but as the errors indicate, the i0 light curve is very noisy. 56 B S TA R S

lists this as a B3 system (my calculations yield B1.5) of luminosity class III, so this would seem to be another case where at least one of the components is evolved. The EC sample also contains one of the stars which my calculations place into spectral class O – this is the system BD-17 5191s, listed simply as B in SIMBAD, whereas I ﬁnd O6. It has the second shortest period of 0.395328 d and very small and equal ﬂux amplitudes of around 6%, corresponding to around 0.07 mag brightness amplitude in the primary minimum, which is rather in favour of an ellipsoidal variable. With only 41 data points in i0 and 43 data points in r0, it is not yet very well sampled, however. Figure 42 shows the r0 light curve.

Figure 40: Flux-normalised r0 light curve of TYC 8959-350-1, P = 5.38739 d. 4.1 eclipsing binaries 57

Figure 41: Flux-normalised r0 light curve of 2MASS J06401339-0114484, P = 4.17805 d.

Figure 42: Flux-normalised r0 light curve of BD-17 5191s, P = 0.395328 d 58 B S TA R S m 0 e 0.02 0.02 0.088 0.018 0.103 0.071 0.029 0.076 0.023 0.057 0.041 0.046 0.024 0.095 0.024 1 D 0.5 0.44 0.556 0.489 0.513 0.566 0.455 0.519 0.452 0.486 0.464 0.513 0.474 0.471 0.485 0.515 0.240 0.517 0.208 0.324 0.447 0.463 0.272 0.447 0.454 0.406 0.343 0.374 0.398 0.283 0.322 0.464 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.716 0.957 0.851 0.755 0.963 0.847 0.703 0.957 0.824 0.947 0.808 0.819 0.977 0.770 0.644 0.963 p F / s F 0.240 0.515 0.171 0.386 0.444 0.367 0.313 0.456 0.306 0.332 0.271 0.392 0.289 0.269 0.274 0.584 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.744 0.986 0.840 0.765 0.900 0.947 0.885 0.840 0.787 0.963 0.767 0.958 0.823 0.996 0.696 0.993 0.023 0.025 0.031 0.019 0.021 0.031 0.020 0.024 0.024 0.023 0.050 0.028 0.028 0.027 0.028 0.016 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.083 0.063 0.168 0.055 0.062 0.073 0.062 0.070 0.058 0.074 0.151 0.079 0.096 0.091 0.066 0.047 s F 0.025 0.021 0.027 0.021 0.022 0.025 0.019 0.032 0.021 0.020 0.030 0.024 0.022 0.023 0.021 0.027 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.097 0.058 0.173 0.053 0.060 0.088 0.073 0.076 0.068 0.079 0.109 0.082 0.080 0.120 0.064 0.064 0.023 0.025 0.031 0.019 0.021 0.031 0.020 0.024 0.024 0.023 0.050 0.028 0.028 0.027 0.028 0.016 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.116 0.066 0.198 0.073 0.064 0.087 0.088 0.073 0.070 0.078 0.187 0.096 0.098 0.119 0.103 0.049 p F 0.025 0.021 0.027 0.021 0.022 0.025 0.019 0.032 0.021 0.020 0.031 0.024 0.022 0.023 0.021 0.027 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.130 0.059 0.206 0.069 0.067 0.093 0.083 0.091 0.086 0.082 0.141 0.086 0.097 0.121 0.092 0.064 0.010 0.012 0.016 0.011 0.016 0.010 0.013 0.012 0.025 0.013 0.014 0.013 0.015 0.008 0.009 0.007 0 ± ± ± ± ± ± ± ± ± ± ± ± ± i ± ± ± Table 6 : New EC candidates 9.843 9.076 9.905 10.181 10.136 11.452 10.125 10.594 10.516 10.782 11.248 12.767 11.306 11.325 10.790 11.704 0.012 0.010 0.014 0.010 0.012 0.009 0.010 0.010 0.016 0.012 0.011 0.011 0.011 0.009 0.012 0.012 0 ± ± ± ± ± ± ± ± ± ± ± ± ± r ± ± ± Combined brightness/mag 9.751 9.132 9.666 10.242 10.422 11.559 10.045 10.559 10.804 10.862 11.180 12.941 11.243 11.255 10.794 11.774 0.31797 0.39533 1.10139 1.33653 1.50133 1.62283 3.26615 3.39773 3.62641 3.68947 4.17805 4.68877 4.72632 5.38739 6.32693 7.66801 Period/d Period/d – – B1 B5 B2 B3 B0 B6 B2 B4 O6 B1.5 B0.5 B0.5 B1.5 B0.5 GDS B B B B B0 B8 B5 B3 B8 B8 B2 B9 Spectral type B(5) B3III B2IV B9IV/V SIMBAD Name HD 62869 HD 300814 HD 292370 HD 312004 CD-59 5281 LS IV -06 20 BD-17 5191s CD-51 10244 CD-24 5898A TYC 8959-350-1 TYC 4799-714-1 TYC 9011-1728-1 TYC 5699-3842-1 TYC 5125-2757-1 CCDM J06493-0239AB 2MASS J06401339-0114484 4.1 eclipsing binaries 59

PROSPECTIVEESDSYSTEMS

As said before, the dividing line between ESD and EC systems is often not quite clear; like EC systems, most ESD light curves don’t have marked plateaus between the minima. However, as ESD systems are less likely to have equal-temperature components, the minima will usually be more different in depth. In fact, the sample contains several systems with ﬂux amplitude ratios around 0.3 and most are well below 0.9. The sample also contains two stars which my calculations place in spectral class O. The system with the lowest ﬂux amplitude ratio of around 0.3 is HD 328533, which also displays a highly interesting light curve, see Figure 43. It might well be an ED

Figure 43: Flux-normalised r0 light curve of HD 328533, P = 4.65906 d. system, which is hard to decide without modelling; I put it into the ESD category because of the gentle slope between the sharp minima, which could point to an extended envelope around the hotter star – this moves ﬁrst in front of the cooler star, causing the gentler slope (the envelope would thicken towards the core), then the core eclipses the cooler star. The system would have to be quite close because the primary eclipse would occur very soon after the cooler star has moved out from behind the other star’s envelope. In view of the large primary ﬂux amplitude the system’s inclination must be quite high – if it were indeed around 90◦, the sharpness of the minima would imply that the stars have equal radii; in the hypothesis presented above, the hotter star’s core would have to be of the same size as the other star. In the general case, for two stars to 60 B S TA R S

have the same radius but distinctly different temperatures, they would have to be in different stages of development. The combined spectral type according to SIMBAD is B9, while our data point to B3.5. This system is obviously a prime candidate for future modelling. The system with the second lowest flux amplitude ratio, HD 150723, is also very interesting, see Figure 44. This looks like a classic example of the so-called reflection effect, where one hemisphere of the cooler star is heated by the hotter star and one sees most of that hemisphere just before the former is eclipsed. Thus, the brightness rises before the eclipse. Again, the inclination is probably quite high and here, too, it seems likely that one star is in a more developed state than the other. SIMBAD lists a spectral type of B8, my algorithm finds a much earlier B1.5.

Figure 44: Flux-normalised i0 light curve of HD 150723, P = 4.70469 d.

In this sample, too, there is one system which is entered in the WDS and the CCDM, carrying the designation CCDM J16349-5242AB. Here, the visible components are 4” apart from each other and they are of similar brightness, with 10.06 mag and 10.92 mag in V. Again, we cannot resolve this pair; for the combined spectral type we get B4.5, while SIMBAD and the WDS list B8/9V, so the latter might in fact be the spectral type of one of the components, even though this is not made clear in the listing. Unfor- tunately, proper motion data are only available for the primary component and the distance to the stars is unknown, so at this point there is no telling if it is a binary, in 4.1 eclipsing binaries 61 which case our data might turn it into a triple system. But in any event, our light curve is not well sampled yet with only 30 data points in r0 and 23 in i0. Another highly interesting case for which we do have a reasonably good light curve in r0 at least with 109 data points is CPD-59 2618, which has already been mentioned in connection with eccentricity. This is listed as a young stellar object (YSO) in SIMBAD, as well as an X-ray and infrared source and a member of the Carina complex, one of the largest, most active star formation regions in the Galaxy. Figure 45 shows the r0 light curve. There seem to be two stars of different temperatures on a very tight but also slightly eccentric orbit (emin = 0.15). SIMBAD lists the system’s spectral type as B1.5V, I find a slightly earlier B0.5, so in any case, the system must indeed be quite young. Finally, a very well-defined ESD light curve is displayed by [ICS99 A], see Figure 46. It is listed as a B0V star in SIMBAD, unfortunately, in this case we don’t have the requisite UBV data. The light curve shows the largest flux amplitude of the sample, making this system the best candidate for an edge-on system, i.e. close to 90◦ inclination. As such, the light curve would imply components of equal radius, since the minima show no plateau at the bottom. At the same time, the components would have to be of different temperature for the minima to be so different in depth, thus implying two stars in different stages of development. 62 B S TA R S

Figure 45: Flux-normalised r0 light curve of CPD-59 2618, P = 0.97187 d.

Figure 46: Flux-normalised r0 light curve of [ICS99 A], P = 3.48027 d. 4.1 eclipsing binaries 63 m 0 0 e 0.15 0.01 0.01 0.04 0.007 0.005 0.035 0.094 0.057 0.023 0.023 0.036 0.005 0.003 0.003 0.039 0.044 0.132 0.086 0.076 1 D 0.5 0.5 0.56 0.496 0.405 0.503 0.507 0.522 0.536 0.515 0.486 0.523 0.504 0.507 0.475 0.498 0.502 0.525 0.472 0.584 0.555 0.549 0.211 0.189 0.246 0.333 0.263 0.215 0.303 0.246 0.213 0.192 0.178 0.161 0.241 0.260 0.282 0.072 0.120 0.167 0.380 0.366 0.199 0.274 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.645 0.659 0.860 0.393 0.973 0.838 0.862 0.729 0.707 0.798 0.303 0.705 0.873 0.700 0.822 0.331 0.345 0.746 0.846 0.849 0.833 0.808 p F / s F 0.151 0.160 0.221 0.274 0.197 0.152 0.307 0.217 0.196 0.218 0.204 0.165 0.176 0.248 0.247 0.073 0.144 0.266 0.334 0.463 0.279 0.339 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.534 0.691 0.885 0.440 0.855 0.835 0.658 0.743 0.654 0.792 0.343 0.678 0.724 0.717 0.708 0.255 0.317 0.775 0.749 0.995 0.979 0.932 0.042 0.034 0.024 0.030 0.024 0.032 0.022 0.027 0.024 0.022 0.024 0.051 0.026 0.023 0.025 0.023 0.025 0.021 0.026 0.023 0.026 0.019 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.153 0.144 0.111 0.038 0.126 0.165 0.083 0.101 0.096 0.116 0.042 0.280 0.126 0.076 0.094 0.114 0.074 0.119 0.076 0.071 0.141 0.074 s F 0.032 0.026 0.020 0.024 0.023 0.024 0.023 0.025 0.024 0.025 0.029 0.052 0.024 0.022 0.026 0.025 0.029 0.033 0.034 0.026 0.029 0.026 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.129 0.138 0.104 0.042 0.133 0.170 0.059 0.105 0.098 0.116 0.052 0.264 0.120 0.080 0.092 0.089 0.066 0.120 0.094 0.077 0.142 0.097 0.043 0.035 0.024 0.030 0.024 0.033 0.022 0.028 0.024 0.022 0.024 0.055 0.026 0.023 0.025 0.024 0.024 0.021 0.026 0.023 0.026 0.020 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.237 0.219 0.129 0.097 0.129 0.197 0.096 0.138 0.136 0.145 0.138 0.397 0.144 0.108 0.114 0.344 0.216 0.160 0.090 0.084 0.170 0.092 p F 0.033 0.026 0.020 0.024 0.023 0.024 0.023 0.025 0.024 0.025 0.029 0.056 0.024 0.022 0.026 0.025 0.029 0.032 0.033 0.026 0.029 0.026 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.242 0.200 0.118 0.095 0.155 0.204 0.089 0.141 0.149 0.146 0.152 0.389 0.166 0.111 0.130 0.348 0.209 0.154 0.126 0.078 0.145 0.104 0.021 0.018 0.012 0.015 0.013 0.016 0.010 0.014 0.011 0.010 0.011 0.023 0.012 0.011 0.012 0.009 0.011 0.009 0.009 0.010 0.010 0.011 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± i ± ± ± ± ± ± Table 7 : New ESD candidates 9.860 9.098 9.261 9.097 9.760 9.568 12.237 11.597 11.374 11.140 11.310 11.334 10.044 10.571 10.870 10.162 10.114 12.762 10.098 11.037 10.609 10.715 0.019 0.014 0.010 0.012 0.012 0.012 0.010 0.012 0.012 0.012 0.014 0.024 0.012 0.011 0.013 0.012 0.014 0.011 0.013 0.013 0.011 0.014 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± r ± ± ± ± ± Combined brightness/mag 9.147 9.210 9.093 9.636 9.993 12.319 11.652 11.318 11.087 11.261 11.239 10.019 10.425 10.989 10.183 10.034 13.877 10.355 11.207 10.254 10.598 11.032 0.6965 0.97187 1.25406 1.41801 1.51567 1.60403 2.69721 2.73019 2.87173 2.92956 3.07533 3.48027 3.65435 4.12971 4.37358 4.65906 4.70469 4.88617 7.35411 7.46751 8.14739 13.1023 Period/d Period/d – – – B2 B4 B3 B4 B5 B2 B0 O5 O5 B0.5 B2.5 B2.5 B4.5 B1.5 B3.5 B1.5 B1.5 B4.5 B0.5 GDS B B B B7 B8 B8 B9 B8 B5 B8 B9 B8 B8 B2 B3: B... Spectral type B0V B1/3 B1.5V B4/B5 B8/9V B9IV/V SIMBAD A ] Name ICS99 [ HD 66647 HD 306429 HD 306392 HD 306140 HD 304241 HD 300349 HD 312037 HD 328533 HD 150723 HD 322453 HD 300777 BD-02 4797 BD-03 4416 CD-26 4800 CD-51 9509 LS IV -11 22 CPD-59 2618 CPD-63 3284 TYC 4805-1594-1 GSC 05692-01147 CCDM J16349-5242AB 64 B S TA R S

PROSPECTIVEEDSYSTEMS

The ED sample contains some of the systems with eccentricities higher than 0.2, among them the new high eccentricity EBs from Table 5.

The system with the highest eccentricity of emin = 0.264 in the entire sample of new EBs is HD 168862. The r0 light curve is shown in Figure 47. There is a rise in flux just after the secondary minimum before the descent into the primary minimum begins, but there is no equivalent on the other side of the secondary minimum, thus making the explanation of this being a reflection effect somewhat improbable, nor do I see any other obvious explanation for this asymmetry. In any case, with the large flux amplitude, a flux amplitude ratio of around 0.7 and quite sharp minima, we would again seem to have a system consisting of two stars in different stages of development. The spectral type given in SIMBAD is B3II (I find B0), thus already implying one evolved component.

Figure 47: Flux-normalised r0 light curve of HD 168862, P = 4.44639 d.

The second highest eccentricity of emin = 0.207 belongs to HD 60366, as shown in Figure 48. Unfortunately, although the period of P = 4.27526 d found by the classifier is definitely the best folding, the light curve is rather noisy. Apart from that, in one of the rarer cases among the ED sample the sharp minima are of virtually equal depth with rather small flux amplitudes of about 0.13 to 0.14. If one is to interpret this as an 4.1 eclipsing binaries 65

EB light curve, it would belong to a system with probably rather low inclination and an eccentric orbit. The spectral type in SIMBAD is given as B9III, whereas I ﬁnd B3.5.

Figure 48: Flux-normalised r0 light curve of HD 60366, P = 4.27526 d.

The third candidate from the high eccentricity list is CPD-26 2634, with emin = 0.202, see Figure 49. Although the minima are very sparsely sampled, the fact they are observed at the same time in both filters lends this case credibility. Shown in Figure 49 is the better sampled r0 light curve, which displays a large primary flux amplitude of 0.34 and a flux amplitude ratio of 0.48. So again, this implies a large inclination and components of distinctly different temperatures, but similar sizes. For the spectral type, SIMBAD lists B9III (I find B6), thus already suggesting one evolved component. Contained in this sample is also another candidate which is listed both in the WDS and the CCDM and where we have definitely detected the primary component. HD 53542 shows a combined brightness of 9.356 ± 0.010 mag in r0 (we do not have i0 measurements at this point); the WDS lists the primary’s visual brightness at 9.46 mag, while the secondary’s visual brightness is given as 13.5 mag. It is located at an angular distance of 3" from the primary. There is no information on the distance to this system, however, the spectral type is listed as B9/A0V in SIMBAD and A0 in the WDS, while my calculations yield B7.5. Assuming the luminosity classification as a main sequence star to be correct, we may use the associated absolute visual magnitude of MV = 0.58 for spectral class A0V and the distance modulus to estimate an approximate lower-limit 66 B S TA R S

Figure 49: Flux-normalised r0 light curve of CPD-26 2634, P = 5.47088 d.

(a B7.5 star would be intrinsically brighter) distance to the system. With the apparent

visual magnitude mV = 9.46, it would put the system at a distance of about 597 pc from the Sun, implying a separation of 8.68 · 10−3 pc or 1791 AU between the components listed in the WDS. This would constitute a very wide binary and somewhat lessens the probability of the discovery of a triple system, especially since the assumption of the primary being a main sequence star yields only a lower limit on the distance, for a giant/supergiant would naturally be much more luminous. Our light curve, while not well sampled yet, in any case shows significant drops in brightness of 18 and 20% in a manner that would suggest the primary component might be a slightly eccentric detached binary system, see Figure 50 (in view of the short period an interpretation as ESD is also possible). A much clearer case in terms of configuration is presented by HD 295887, the system with the lowest flux amplitude ratio of all new systems in both filters of around 0.29, as shown in Figure 51. The primary minimum is also quite deep with 25-26%, so we might have a nearly edge-on system here where both components would be of about equal size, given the sharpness of the minima, and of very different temperatures, so quite certainly another system composed of stars in different stages of development. The spectral type given by SIMBAD is B9, my algorithm yields B8. 4.1 eclipsing binaries 67

Figure 50: Flux-normalised r0 light curve of HD 53542, P = 2.38978 d.

Figure 51: Flux-normalised r0 light curve of HD 295887, P = 4.69846 d. 68 B S TA R S m e 0.01 0.01 0.029 0.015 0.083 0.009 0.006 0.004 0.037 0.012 0.011 0.207 0.264 0.015 0.001 0.053 0.017 0.202 0.168 0.001 0.125 0.005 0.001 0.011 0.158 1 D 0.5 0.6 0.51 0.482 0.491 0.553 0.506 0.496 0.498 0.494 0.524 0.493 0.493 0.369 0.666 0.501 0.494 0.467 0.511 0.628 0.607 0.421 0.497 0.501 0.493 0.119 0.130 0.089 0.078 0.185 0.149 0.186 0.369 0.217 0.172 0.141 0.176 0.082 0.181 0.214 0.171 0.113 0.108 0.361 0.166 0.104 0.162 0.190 0.092 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± −− 0.354 0.520 0.470 0.342 0.533 0.341 0.458 0.900 0.802 0.885 0.691 0.834 0.292 0.733 0.576 0.652 0.687 0.556 0.989 0.860 0.823 0.804 0.701 0.962 p F / s F 0.098 0.133 0.160 0.093 0.083 0.252 0.149 0.084 0.417 0.215 0.278 0.152 0.181 0.097 0.202 0.257 0.187 0.073 0.148 0.230 0.115 0.108 0.156 0.230 0.108 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.428 0.477 0.853 0.744 0.281 0.529 0.388 0.271 0.836 0.781 0.936 0.728 0.760 0.286 0.743 0.618 0.582 0.484 0.603 0.908 0.909 0.951 0.832 0.822 0.953 0.027 0.023 0.020 0.022 0.023 0.021 0.041 0.020 0.021 0.018 0.025 0.023 0.020 0.022 0.022 0.028 0.023 0.021 0.032 0.037 0.026 0.025 0.020 0.021 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± −− 0.086 0.105 0.136 0.101 0.075 0.050 0.113 0.066 0.097 0.125 0.150 0.145 0.073 0.108 0.070 0.126 0.171 0.126 0.123 0.258 0.273 0.156 0.092 0.298 s F 0.022 0.025 0.025 0.021 0.025 0.035 0.021 0.026 0.027 0.023 0.030 0.028 0.025 0.024 0.024 0.028 0.034 0.022 0.031 0.024 0.025 0.027 0.023 0.022 0.026 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.107 0.101 0.175 0.213 0.090 0.083 0.060 0.088 0.071 0.104 0.136 0.164 0.133 0.075 0.112 0.079 0.122 0.163 0.149 0.130 0.273 0.327 0.162 0.100 0.316 0.028 0.023 0.023 0.022 0.023 0.021 0.042 0.020 0.021 0.018 0.025 0.024 0.020 0.022 0.023 0.028 0.023 0.022 0.032 0.038 0.027 0.025 0.020 0.021 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± −− 0.243 0.203 0.288 0.296 0.141 0.148 0.246 0.073 0.121 0.142 0.218 0.174 0.251 0.147 0.121 0.193 0.249 0.227 0.124 0.300 0.332 0.194 0.131 0.309 p F 0.022 0.025 0.025 0.021 0.026 0.035 0.021 0.027 0.027 0.023 0.030 0.028 0.025 0.024 0.024 0.028 0.034 0.022 0.031 0.024 0.026 0.027 0.023 0.022 0.026 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.249 0.212 0.205 0.286 0.320 0.157 0.154 0.324 0.085 0.134 0.146 0.226 0.175 0.262 0.150 0.128 0.210 0.336 0.247 0.143 0.301 0.344 0.195 0.122 0.332 0.013 0.011 0.010 0.010 0.010 0.010 0.023 0.010 0.008 0.011 0.009 0.010 0.011 0.014 0.011 0.010 0.016 0.020 0.012 0.012 0.009 0.010 0.009 0.010 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Table 8 : New ED candidates i ± ± −− 9.587 9.199 10.906 10.401 10.020 10.630 10.269 10.467 11.979 10.276 10.132 11.125 10.679 10.206 10.447 10.321 11.342 10.306 11.410 11.531 11.444 10.610 10.060 10.264 0.011 0.012 0.012 0.019 0.010 0.014 0.010 0.014 0.013 0.013 0.011 0.015 0.018 0.011 0.017 0.013 0.013 0.015 0.012 0.011 0.013 0.010 0.010 0.011 0.011 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± r ± ± ± ± Combined brightness/mag 9.356 9.983 9.372 9.301 10.767 10.382 10.554 10.179 10.627 11.956 10.309 10.033 11.514 10.566 10.195 10.593 10.231 11.231 10.597 11.345 11.528 11.586 10.697 10.368 10.252 3.4272 1.31948 2.24361 2.38978 2.81131 3.19303 3.26096 3.48297 3.88224 3.88406 4.27526 4.44639 4.44739 4.69846 4.79262 4.86222 5.27888 5.47088 5.69026 6.21639 6.60925 7.55718 7.77073 14.1852 24.8070 Period/d B6 B5 B1 B7 B0 B2 B8 B6 B0 B5 B3 B2 B2.5 B7.5 B2.5 B1.5 B2.5 B2.5 B3.5 B3.5 B2.5 B0.5 B2.5 B2.5 B0.5 GDS B B B B8 B3 B2 B5 B9 B9 B9 B3 B5 B8 B9 B9 B5 B... Spectral type B3II B9V B9III B9III B8/9III B9/A0V SIMBAD B8/9II/III B5/8IV/V Name HD 53542 HD 54436 HD 60366 HD 306745 HD 146629 HD 140823 HD 146292 HD 302981 HD 326476 HD 168862 HD 295887 HD 316017 HD 305842 HD 308648 HD 326732 HD 326704 HD 323068 HD 322270 CD-52 7093 CPD-26 2634 CPD-59 5411 TYC 8319-650-1 UCAC2 5319779 TYC 5385-1027-1 TYC 8995-2720-1 4.1 eclipsing binaries 69

4.1.2EBCANDIDATESWITHDIFFERENTCATALOGUECLASSIFICATION

Of the seven systems in this category, I would preliminarily class four as EC, two as ESD and one as ED. Starting with the potential ED system, Figure 52 shows the r0 light curve of CD-59 5583 (ASAS J151510-5928.8 in the VSX), a system which is not strictly of different classification, but entered as undecided between EC, ESD and DCEP-FO, the latter being a type of Cepheid, i.e. pulsating star. We find roughly the same period as the one given in the VSX, ours is 8.70544 d, the VSX lists 8.70747 d, which does not result in a discernible difference in the folded light curve. Although the light curve is not particularly well sampled, it would seem to be in favour of the detached EB configuration with a decisively eccentric orbit (e & 0.25). The comparatively small amplitudes suggest that the inclination would be well below 90◦. The system is catalogued in SIMBAD as a B0II star, according to our data it might even be an O5 system.

Figure 52: Flux-normalised r0 light curve of CD-59 5583, P = 8.70544 d.

The longest period in this sample belongs to a potential EC system, HD 295557, with P = 9.55283 d, see Figure 53. According to the VSX, this is an ACV (rotating) variable. The primary amplitude of 0.104 ± 0.020 mag in r0 and 0.106 ± 0.025 mag in i0 would be at the upper end of the usual amplitude range for this class (as well as for ellipsoidal variables); the period given in the VSX is almost exactly half the period we ﬁnd; folding our data with the VSX period of P = 4.7701 d, however, yields a decidedly worse ﬁt 70 B S TA R S

with larger scattering than for our period. SIMBAD lists this as a B9 star, our data point to B5, which would be too early for an ACV variable, however, a deﬁnite conclusion on this would need spectroscopic data. In the interpretation of an EC system, we would need to have a comparatively low inclination because of the small ﬂux amplitude.

Figure 53: Flux-normalised r0 light curve of HD 295557, P = 9.55283 d.

The other three EC candidates are HD 150792, CD-56 5767 and V724 Car. The first one is listed as a rotating ellipsoidal variable under the designation NSVS 12577612 in the VSX. We find a period similar the one given there, the latter is 4.7701 d, while ours amounts to 4.2394 d; the difference in the folded light curves is negligible. The magnitude range of about 9.3 to 9.5 mag is compatible with the VSX in both filters (9.38 to 9.50 in V according to the VSX). However, the primary brightness amplitude I calculate would be rather too large for an ellipsoidal variable, with 0.119 ± 0.022 mag in r0 and 0.130 ± 0.019 mag in i0. But since the light curve is still very sparsely sampled in both filters (34 data points in r0, 30 in i0), a definite conclusion will have to await further measurements. The spectral type is given as B5/7II in SIMBAD, whereas I calculate B1.5. The r0 light curve is displayed in Figure 54. CD-56 5767 is listed in the VSX under the designation ASAS J151113-5721.2 as undecided between ACV|EC|ESD with a period of 0.94555 d, whereas we find the best fit to our data for roughly twice this period, P = 1.89107 d, as shown in Figure 55. With a primary brightness amplitude of 0.108 ± 0.024 mag in r0 and 0.089 ± 0.020 mag 4.1 eclipsing binaries 71

Figure 54: Flux-normalised r0 light curve of HD 150792, P = 4.2394 d. in i0 it is just at the uppermost limit for an ACV variable. The spectral type is given simply as B, my calculations indicate it might even be an O7 star, which would rule out the ACV interpretation, as these variables are of spectral types B8p-A7p. All in all, our data would seem to be in favour of an EC system, but a definite conclusion should await spectroscopic measurements. V724 Car is listed in the VSX as a beta Cephei pulsating variable of spectral type B1V with a period of 0.451686 d. We find a period of twice the VSX period, which would be too long for a beta Cephei variable (periods range between 0.1 and 0.6 days). In this case, however, the foldings work equally well and with the small amount of data points available to us – 30 in r0, 27 in i0 – a definite conclusion can not be drawn at this time. Shown in Figure 56 is the r0 light curve. The two potential ESD systems – which could both also be classed as EC – are HD 292711 and HD 302532. The former is simply entered as VAR in the VSX, i.e. a variable of unknown type, under the designation ASAS J065427-0023.1. For this object we have a well-sampled light curve in r0 and i0, Figure 57 shows the r0 light curve. The period given in the VSX, P = 5.5272 d, is roughly equal to our own, P = 5.53059 d, but the latter produces a somewhat less noisy light curve. If this object is interpreted as an EC, it would have to have a rather small inclination, as can be gathered from the small flux amplitudes. The brightness amplitude of the primary minimum is with 0.093 ± 0.018 72 B S TA R S

Figure 55: Flux-normalised r0 light curve of CD-56 5767, P = 1.89107 d.

Figure 56: Flux-normalised r0 light curve of V 724 Car, P = 0.90339 d. 4.1 eclipsing binaries 73 mag in r0 and 0.098 ± 0.023 mag in i0 also small enough for an ellipsoidal variable. Whatever its nature, the spectral type is probably late B, as my algorithm finds B7, and SIMBAD lists B8. HD 302532 is listed in the VSX as an ellipsoidal variable star of spectral type B0V (B3 according to SIMBAD, whereas our data support the VSX spectral type) with a period of 3.75806 d, which we basically match, finding P = 3.75807 d. In our still sparsely sampled light curve, one clearly sees two minima of different depth, amounting to a flux amplitude ratio of 0.65 to 0.73, depending on the filter. The brightness amplitude is rather too large for an ellipsoidal variable, with 0.161 ± 0.022 mag in r0 and 0.159 ± 0.022 mag in i0 in the primary minimum – even for the secondary amplitude, we find 0.114 ± 0.022 mag in r0 and 0.101 ± 0.022 mag in i0. Again, however, we have only 45 measurements in r0 and 44 in i0, so for a definite decision more data should be gathered. Figure 58 shows the r0 light curve. Detailed data on all of these systems may be found in Table 10 in Appendix A. 74 B S TA R S

Figure 57: Flux-normalised r0 light curve of HD 292711, P = 5.53059 d.

Figure 58: Flux-normalised r0 light curve of HD 302532, P = 3.75807 d. 4.1 eclipsing binaries 75

4.1.3KNOWNECLIPSINGBINARIES

The group of already known EBs comprises 167 members. Figure 59 shows a plot of our periods versus the periods given in the VSX, where for reasons of clarity the four systems with P > 20 d have been omitted (of these, two are in agreement with the VSX, the other two cases will be discussed below). Obviously there is a very good agreement for the largest part.

Figure 59: GDS periods versus VSX periods.

In most of the 23 cases where VSX and GDS period differ significantly (i.e. ∆P > 0.05 d), the VSX period is the best fit, except for the following three cases, in which there is either no clear preference or our period provides the better fit. Here I have plotted magnitudes instead of flux against the phase for easier comparison with catalogue data. Starting with the longest catalogue period of 30.811 d for V493 Sct, in this case we find roughly half this period, however we only have data in i0 for this system and with 22 data points very few at that, so a definite decision has to await further observations. The system is supposed to be an Algol-type detached EB – which our period would still support – of spectral type B0.5Ib. In this case we lack UBV data. It should be noted that the system is quite well studied, with data on the brightness in the secondary 76 B S TA R S

minimum – 8.52 mag in V – and the phase difference between the minima, 0.75. The latter obviously doesn’t match the folding of our data with our period. The brightness in the secondary minimum also differs slightly from the catalogue value, we measure 8.093 ± 0.025 mag in the secondary minimum (this may be due to lack of data points in the minimum, however and/or the different ﬁlters) and a phase difference of 0.552 from primary to secondary minimum. Figure 60 shows a comparison of the light curve folded with the catalogue vs. our period.

Figure 60: i0 light curves of V493 Sct, left: catalogue period P = 30.811 d, right: our period P = 14.3326 d

The next system, V778 Sgr, provides a much clearer case, as can be gathered from Figure 61. While it can be folded with the VSX period, which is twice our period, this obviously does not make sense if this is to be a EB system, while with our period we have a clear case of what is most likely a semi-detached EB (the VSX lists it as a detached Algol-type system, but our short period together with the shape of the light curve makes an ESD configuration more likely). The brightness range is listed in the VSX as 11.7 - 12.2 mag and the brightness in the secondary minimum as 12.1 mag. The former obviously agrees well with our data, while the secondary minimum is brighter according to our data. However, the VSX does not state which filter was used. The spectral type for this system is given as B8 in SIMBAD, while we find B5. The third system is DT Pup, categorised as a detached β Lyrae type system with a period of 3.34342 d in the VSX, while we find a period of 4.94246 d. Figure 62 shows the folded light curves for both periods. Of course, with only 34 data points in the r0 filter (and 19 in i0), a definite decision is hazardous at this point, however the VSX’ own classification of the system as β Lyrae is rather in support of our period. In β Lyrae type systems, the secondary minimum is typically decidedly less deep than the 4.1 eclipsing binaries 77

Figure 61: r0 light curves of V0778 Sgr, left: catalogue period P = 4.0576 d, right: our period P = 2.02882 d

Figure 62: r0 light curves of DT Pup, left: catalogue period P = 3.34342 d, right: our period P = 4.94246 d. primary, which is clearly the case for our folding, but much less so for the VSX period. The spectral type given by SIMBAD is B3, our data point to B5. Earlier in this chapter, the system HD 97726 was mentioned as having the longest period in the entire sample and which was only detected by Fein’s algorithm because it found a much shorter period of 0.670942 d. The period according to the VSX is 74.64 d and folding our data with this period provides us with a very well-deﬁned ESD light curve which also displays another version of the phenomenon seen earlier for TYC 8959-350-1 and HD 328533 in subsection 4.1.1 – here, the primary minimum starts with a smaller slope before plunging much more steeply down to its lowest point and vice versa for the egress. The secondary minimum has a more uniform shape and is more rounded at the bottom than the primary minimum. In the VSX the system is listed as an Algol-type EB containing one or two giants/supergiants. The peculiar 78 B S TA R S

shape of the light curve might thus be explained as a result of the extended envelope of the giant/supergiant component. SIMBAD lists the system’s spectral type as B9, whereas I find B4. Incidentally, this is a case where lack of measurements in one filter would lead to an underestimation of the minima depth, as Figure 63 illustrates. In the VSX the magnitude range is given as 9.3 to 9.8, whereas our data place it at 8.975 ± 0.016 - 9.709 ± 0.026 mag in r0, however, the VSX magnitude range is only given without reference to a filter.

Figure 63: Light curve of HD 97726. Left r0, right i0. P = 74.64 d.

Detailed data on all known EBs may be found in Table 11 in Appendix A. 5 SUMMARYANDOUTLOOK

By cross-matching the GDS data with existing catalogues, I was able to demonstrate that the GDS contains representatives of basically every variety of variable star. Fur- thermore it turned out that ∼ 90% of the variable sources contained in the survey were not even known as such before and that ∼ 51% of the known variables have not been classified yet. These findings alone show that the GDS is a goldmine for a wide range of variability studies and a perfect testing ground for automated light curve classifiers like the one by C. Fein whose results I have utilised for the work presented here. Investigating the distribution of variable stars over spectral classes I found that the B stars are in fact the most prominent group right alongside the M stars. While for the latter their prevalence is not surprising simply on the ground of their being the most common type of star in the Galaxy, B stars are comparatively rare and the fact that they feature so prominently in this survey of variable sources points to intrinsic high variability. Looking at the distribution of variable types within each spectral class, I found that the variability among the B stars appears to be mainly due to EBs and that the fraction of EBs decreases to later spectral types. Furthermore, my calculations of spectral types for the EB candidates I selected from C. Fein’s sample indicate that a number of stars that have up to now been classified as B may in fact be O stars, thus potentially increasing the fraction of EBs at the high end of the mass spectrum. However, additional measurements are needed here for confirmation. Determining the phase positions of the EB minima allowed me to calculate lower limits for the orbital eccentricities of the 237 selected EB candidates. I was thus able to identify eight systems with e & 0.2, three of which are GDS discoveries, while for the others the catalogue data were confirmed. These systems are prime candidates for follow-up studies which could try to detect orbit precession, thus potentially providing information on the stars’ internal structure. Among the selected sample of new EBs there are 16 candidates for contact systems which are also interesting for future studies which might look for signs of interactions between the component stars. The low flux amplitudes of ∼0.06 to ∼0.2 indicate that these systems have either very low inclinations or may in fact be rotating ellipsoidal variables. The latter would still mark the discovery of new binary systems. For half

79 80 S U M M A RY A N D O U T L O O K

of the prospective EC systems, their brightness amplitudes of more than 1 mag are in favour of interpreting them as EBs. Periods are, unsurprisingly, at the lower end of the range found for the entire sample, with P ≈ 0.32 d to P ≈ 7.7 d Among the 22 ESD candidates, a case of indirect interaction in the shape of heating can be inferred directly from the light curve. In this class, as well as the ED category (25 systems), larger ﬂux amplitudes of up to ∼0.4 and ∼0.3 are found, respectively, thus providing several candidates with potentially higher inclinations. Temperature differences between the components are generally more pronounced in these two classes. As might be expected, periods are distributed over a larger range than those of the ECs, spanning ∼0.7 d to ∼13 d for the ESD systems and ∼1.3 d to ∼25 d in the ED category. Apart from additional photometric studies, spectroscopy would be desirable for selected EB candidates in order to determine the spectral types of the components stars, thus providing a better groundwork for detailed computational modelling. A APPENDIXA-TABLES

A.1AMPLITUDESANDECCENTRICITIES

The spectral types (ST) in these tables are those listed in SIMBAD. Ap and As are primary and secondary amplitude, respectively. They are given in magnitudes here for easier comparison with catalogue data. D1 is the phase difference from primary to secondary minimum and emin is the calculated lower limit for the orbital eccentricity.

81 82 A P P E N D I X A - TA B L E S 0 – 0 i 0.11 0.15 0.089 0.039 0.002 0.126 0.008 0.005 0.034 0.213 0.041 0.126 0.021 0.034 0.013 0.034 0.042 0.059 0.051 0.007 0.042 0.006 0.001 0.091 0.021 0.064 0.087 0.006 min e 0 r 0.15 0.01 0.089 0.003 0.012 0.174 0.032 0.005 0.024 0.006 0.061 0.016 0.021 0.034 0.013 0.005 0.083 0.077 0.071 0.042 0.097 0.052 0.031 0.006 0.009 0.003 0.021 0.031 0.042 0.014 0 – i 0.5 0.42 0.42 0.57 0.54 0.556 0.475 0.499 0.505 0.503 0.478 0.635 0.474 0.513 0.522 0.492 0.478 0.527 0.538 0.467 0.504 0.527 0.496 0.501 0.442 0.405 0.487 0.444 0.504 1 D 0 r 0.39 0.52 0.49 0.52 0.556 0.502 0.492 0.503 0.485 0.496 0.539 0.487 0.522 0.508 0.503 0.553 0.549 0.545 0.473 0.562 0.467 0.519 0.496 0.494 0.595 0.498 0.487 0.507 0.527 0.509 0.02 0.02 0.02 0.02 0.05 0.021 0.033 0.023 0.025 0.016 0.028 0.017 0.023 0.031 0.027 0.021 0.019 0.025 0.019 0.022 0.019 0.017 0.019 0.022 0.022 0.04 0.041 0.018 0.03 0 ± ± ± ± ± – i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.2 0.13 0.094 0.18 0.046 0.116 0.085 0.07 0.356 0.071 0.169 0.128 0.097 0.062 0.042 0.069 0.146 0.196 0.083 0.121 0.094 0.115 0.158 0.109 0.133 0.079 0.056 0.064 0.146 /mag s A 0.02 0.03 0.022 0.019 0.025 0.026 0.019 0.021 0.017 0.022 0.019 0.022 0.022 0.023 0.019 0.023 0.022 0.025 0.023 0.018 0.022 0.019 0.052 0.019 0.021 0.031 0.022 0.018 0.022 0.025 0 ± ± r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.1 0.1 0.15 0.066 0.12 0.26 0.094 0.111 0.065 0.162 0.206 0.119 0.122 0.059 0.047 0.068 0.154 0.202 0.116 0.208 0.111 0.134 0.058 0.102 0.083 0.086 0.067 0.332 0.076 0.139 0.02 0.03 0.02 0.02 0.02 0.021 0.042 0.034 0.026 0.016 0.017 0.031 0.027 0.021 0.019 0.025 0.019 0.022 0.017 0.019 0.054 0.041 0.022 0.022 0.023 0.028 0.023 0.019 0.018 0 ± ± ± ± ± – i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.1 0.134 0.239 0.15 0.11 0.15 0.17 0.161 0.381 0.165 0.074 0.294 0.269 0.302 0.082 0.072 0.238 0.098 0.246 0.109 0.161 0.369 0.158 0.082 0.174 0.549 0.307 0.079 0.169 /mag p A 0.02 0.03 0.02 0.022 0.019 0.032 0.025 0.019 0.021 0.017 0.022 0.019 0.022 0.022 0.022 0.023 0.019 0.022 0.018 0.023 0.022 0.025 0.023 0.018 0.022 0.056 0.026 0.019 0.021 0.026 0 ± ± ± r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.25 0.101 0.185 0.182 0.152 0.066 0.301 0.242 0.136 0.311 0.078 0.109 0.075 0.183 0.247 0.106 0.259 0.249 0.165 0.366 0.175 0.172 0.179 0.418 0.094 0.103 0.535 0.425 0.098 0.197 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.012 0.021 0.018 0.016 0.012 0.013 0.011 0.016 0.016 0.011 0.014 0.011 0.023 0.023 0.013 0.012 0.008 0.015 0.013 0.011 0.009 ± ± ± ± ± ± 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± – i ± ± ± ± ± 10.02 10.63 10.181 9.843 11.14 11.31 10.044 10.87 10.162 10.269 10.516 9.076 10.467 10.136 12.237 11.597 11.452 11.374 10.906 10.125 11.334 10.594 10.401 10.571 10.114 12.762 11.979 10.782 10.098 Table 9 : New EB candidates 0.01 0.01 0.01 0.01 0.01 0.01 0.012 0.019 0.014 0.014 0.011 0.012 0.012 0.012 0.012 0.012 0.01 0.012 0.01 0.012 0.012 0.014 0.012 0.019 0.009 0.024 0.014 0.012 0.009 0.012 ± ± ± ± ± ± 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± r ± ± Combined brightness 9.356 9.983 10.422 11.318 9.751 10.045 10.019 9.132 10.627 10.862 10.242 12.319 11.652 11.559 10.767 11.087 11.261 11.239 10.559 10.382 10.425 10.989 10.183 10.034 10.554 10.179 10.804 13.877 11.956 10.355 0 – i 79 41 42 52 46 94 52 45 45 52 24 57 57 26 54 29 57 36 57 65 51 45 50 111 101 165 102 165 167 0 r 43 51 85 83 58 58 83 31 59 58 58 39 67 35 38 94 83 53 77 Data points 122 109 109 130 115 201 102 201 109 108 209 0.31797 0.97187 1.51567 3.19303 3.48027 0.395328 0.696497 1.101389 1.254063 1.319483 1.336532 1.418014 1.501325 1.604028 1.622831 2.243614 2.389777 2.697206 2.730192 2.811308 2.871728 2.929556 3.075329 3.260956 3.266148 3.397729 3.427195 3.482969 3.626408 3.654345 Period/d B B B B B7 B0 B8 B8 B8 B8 B9 B8 B3 B5 B3 B2 B5 B5 ST B3: B(5) B0V B1/3 B1.5V B4/B5 B8/9III B9IV/V B9IV/V B9/A0V B8/9II/III B5/8IV/V A ] Name ICS99 [ HD 62869 HD 53542 HD 66647 HD 306745 HD 306429 HD 306392 HD 146629 HD 306140 HD 304241 HD 140823 HD 300349 HD 146292 HD 302981 HD 300814 HD 312037 CD-59 5281 CD-26 4800 LS IV -06 20 BD-17 5191s CD-51 10244 CPD-59 2618 CPD-63 3284 UCAC2 5319779 TYC 9011-1728-1 TYC 4805-1594-1 TYC 5699-3842-1 TYC 5385-1027-1 GSC 05692-01147 CCDM J06493-0239AB A.1 amplitudes and eccentricities 83 0 i 0.06 0.01 0.13 0.071 0.007 0.045 0.044 0.205 0.029 0.257 0.004 0.113 0.016 0.038 0.085 0.014 0.041 0.035 0.017 0.003 0.198 0.172 0.003 0.147 0.139 0.056 0.014 0.025 0.021 0.074 0.091 0.011 0.157 min e 0 r 0.02 0.042 0.036 0.015 0.036 0.003 0.211 0.034 0.271 0.003 0.032 0.015 0.041 0.008 0.007 0.064 0.053 0.017 0.004 0.205 0.164 0.001 0.044 0.122 0.126 0.056 0.024 0.022 0.022 0.098 0.062 0.011 0.157 0 i 0.6 0.51 0.455 0.462 0.496 0.472 0.528 0.371 0.518 0.662 0.506 0.502 0.428 0.524 0.446 0.491 0.474 0.478 0.511 0.498 0.625 0.609 0.498 0.407 0.418 0.588 0.536 0.509 0.516 0.487 0.547 0.558 0.493 1 D 0 r 0.6 0.49 0.67 0.52 0.63 0.58 0.473 0.523 0.477 0.498 0.367 0.478 0.513 0.502 0.491 0.526 0.495 0.496 0.459 0.466 0.511 0.497 0.604 0.501 0.472 0.423 0.464 0.484 0.514 0.514 0.562 0.539 0.493 0.02 0.03 0.022 0.016 0.018 0.022 0.049 0.016 0.021 0.018 0.021 0.026 0.018 0.018 0.019 0.016 0.024 0.024 0.022 0.019 0.027 0.036 0.018 0.025 0.014 0.022 0.021 0.018 0.017 0.018 0.022 0.027 0.019 0 ± ± i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.17 0.11 0.079 0.143 0.08 0.083 0.074 0.111 0.085 0.178 0.145 0.107 0.177 0.131 0.089 0.082 0.084 0.124 0.138 0.146 0.104 0.203 0.146 0.074 0.324 0.086 0.347 0.053 0.185 0.165 0.083 0.105 0.383 /mag s A 0.03 0.02 0.02 0.018 0.02 0.025 0.023 0.021 0.024 0.022 0.023 0.022 0.021 0.02 0.021 0.024 0.029 0.021 0.021 0.028 0.023 0.024 0.023 0.026 0.021 0.021 0.024 0.019 0.023 0.021 0.021 0.025 0.024 0 ± ± ± r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.12 0.09 0.08 0.09 0.125 0.09 0.072 0.087 0.11 0.089 0.159 0.105 0.195 0.155 0.101 0.093 0.085 0.074 0.129 0.138 0.142 0.139 0.193 0.175 0.151 0.347 0.107 0.431 0.072 0.192 0.166 0.115 0.413 0.05 0.03 0.02 0.022 0.016 0.022 0.016 0.021 0.018 0.022 0.022 0.018 0.017 0.027 0.019 0.016 0.024 0.024 0.019 0.027 0.036 0.018 0.019 0.026 0.014 0.022 0.021 0.018 0.018 0.018 0.018 0.026 0.022 0 ± ± i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.14 0.14 0.225 0.11 0.31 0.144 0.088 0.082 0.124 0.166 0.131 0.267 0.207 0.458 0.313 0.264 0.112 0.173 0.189 0.233 0.137 0.279 0.118 0.387 0.102 0.095 0.438 0.055 0.235 0.202 0.104 0.153 0.401 /mag p A 0.02 0.03 0.02 0.02 0.02 0.018 0.021 0.021 0.025 0.023 0.021 0.024 0.022 0.023 0.02 0.021 0.025 0.023 0.029 0.021 0.021 0.028 0.023 0.024 0.023 0.026 0.021 0.021 0.024 0.019 0.023 0.022 0.024 0 ± ± ± ± ± r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.11 0.156 0.166 0.33 0.254 0.105 0.088 0.17 0.092 0.097 0.128 0.171 0.151 0.278 0.209 0.464 0.097 0.177 0.149 0.182 0.256 0.139 0.445 0.308 0.168 0.388 0.146 0.459 0.072 0.235 0.119 0.141 0.438 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.012 0.011 0.025 0.008 0.011 0.012 0.013 0.009 0.014 0.011 0.014 0.011 0.015 0.012 0.009 0.009 0.009 0.009 0.013 0.016 0.007 0.012 0.011 0.009 0.01 0.011 ± ± ± ± ± 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± i ± ± ± ± ± ± ± ± ± ± ± 9.76 9.86 9.199 9.097 9.587 10.276 9.098 10.206 9.261 10.79 10.306 11.41 11.531 9.905 10.61 9.568 10.06 10.264 11.248 11.037 12.767 10.132 11.125 10.609 11.306 10.679 11.325 10.447 10.321 11.342 11.704 11.444 10.715 0.01 0.01 0.011 0.016 0.014 0.013 0.013 0.012 0.012 0.013 0.011 0.011 0.015 0.018 0.011 0.011 0.017 0.013 0.011 0.013 0.015 0.012 0.014 0.011 0.013 New EB candidates, continued 0.011 0.011 0.011 0.013 0.011 0.012 0.014 0.013 ± 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± r ± ± ± ± ± ± ± Combined brightness ± 11.18 9.21 9.372 10.309 9.301 9.147 9.093 9.636 9.666 9.993 11.207 12.941 10.033 10.254 11.514 10.598 11.243 10.566 11.255 10.195 10.593 10.231 10.794 11.231 10.597 11.345 11.774 11.528 11.586 10.697 11.032 10.368 10.252 0 i 38 65 79 53 44 43 66 60 59 46 65 57 23 45 38 53 38 25 65 106 110 133 100 163 183 180 186 160 159 118 120 110 168 0 r 62 68 89 66 43 54 69 85 90 30 58 42 66 44 37 68 Data points 137 138 166 110 199 211 212 215 196 189 107 107 155 124 139 109 208 4.17805 4.44639 4.88617 7.66801 3.689465 3.882238 3.884064 4.129707 4.275256 4.373575 4.447394 4.659055 4.688765 4.698463 4.704691 4.726322 4.792621 4.862224 5.278883 5.387394 5.470876 5.690255 6.216387 6.326933 6.609251 7.354106 7.467514 7.557182 7.770734 8.147394 Period/d 13.102302 14.185187 24.807039 B B B B B B B8 B9 B8 B9 B8 B9 B8 B9 B3 B8 B5 B2 B8 B2 B9 B9 B9 B5 ST B... B... B3II B9V B3III B9III B9III B2IV B8/9V Name HD 54436 HD 60366 HD 292370 HD 326476 HD 168862 HD 328533 HD 312004 HD 295887 HD 150723 HD 316017 HD 322453 HD 305842 HD 308648 HD 300777 HD 326732 HD 326704 HD 323068 HD 322270 BD-02 4797 BD-03 4416 CD-51 9509 CD-52 7093 LS IV -11 22 CPD-26 2634 CPD-59 5411 CD-24 5898A TYC 8319-650-1 TYC 8959-350-1 TYC 4799-714-1 TYC 5125-2757-1 TYC 8995-2720-1 CCDM J16349-5242AB 2MASS J06401339-0114484 84 A P P E N D I X A - TA B L E S 0 i 0.041 0.049 0.018 0.041 0.058 0.086 0.018 0.074 0.011 0.014 0.034 0.037 0.045 min 0 e i 0.023 0.046 0.036 0.039 0.006 0.246 0.030 0 r 0.072 0.049 0.018 0.019 0.036 0.036 0.004 0.030 0.004 0.042 0.060 0.037 0.006 min e 0 r 0.023 0.027 0.051 0.026 0.009 0.246 0.033 0 i 0.474 0.469 0.488 0.474 0.463 0.555 0.489 0.453 0.507 0.491 0.521 0.524 0.472 1 D 0 i 0.485 0.529 0.523 0.475 0.504 0.345 0.519 0 r 1 0.454 0.469 0.488 0.488 0.523 0.523 0.498 0.519 0.502 0.526 0.538 0.524 0.496 D 0 r 0.485 0.517 0.533 0.483 0.494 0.655 0.479 0.139 0.032 0.033 0.024 0.026 0.022 0.035 0.022 0.027 0.028 0.031 0.032 0.020 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± 0.021 0.020 0.022 0.019 0.023 0.018 0.025 0.358 0.781 0.240 0.511 0.550 0.168 0.448 0.107 0.504 0.135 0.226 0.129 0.360 0 i ± ± ± ± ± ± ± /mag s A 0.104 0.085 0.101 0.098 0.058 0.103 0.096 0.065 0.032 0.021 0.025 0.019 0.023 0.030 0.020 0.024 0.021 0.022 0.022 0.024 /mag 0 s r ± ± ± ± ± ± ± ± ± ± ± ± ± A 0.033 0.024 0.022 0.022 0.018 0.022 0.020 0.319 0.796 0.220 0.525 0.562 0.185 0.458 0.112 0.534 0.167 0.221 0.122 0.369 0 r ± ± ± ± ± ± ± 0.116 0.088 0.114 0.089 0.039 0.135 0.097 0.145 0.032 0.036 0.024 0.027 0.022 0.036 0.022 0.027 0.028 0.032 0.039 0.020 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± 0.021 0.020 0.022 0.019 0.023 0.018 0.025 0.461 0.857 0.706 0.522 0.597 0.169 0.542 0.160 0.554 0.166 0.276 0.968 0.616 0 i ± ± ± ± ± ± ± /mag p A 0.105 0.089 0.159 0.130 0.098 0.127 0.106 0.066 0.032 0.022 0.025 0.019 0.023 0.031 0.020 0.024 0.021 0.022 0.025 0.024 /mag 0 p r ± ± ± ± ± ± ± ± ± ± ± ± ± A 0.033 0.024 0.022 0.022 0.018 0.022 0.020 0.355 0.844 0.773 0.541 0.573 0.191 0.546 0.162 0.549 0.193 0.283 1.045 0.656 0 r ± ± ± ± ± ± ± 0.116 0.108 0.161 0.119 0.093 0.138 0.104 0.067 0.020 0.020 0.011 0.014 0.019 0.016 0.020 0.020 0.021 0.011 0.013 0.010 0 ± ± ± ± ± ± ± ± ± ± i ± ± ± 0.013 0.016 0.013 0.012 0.013 0.012 0.009 9.741 9.585 9.633 0 14.054 10.298 11.221 11.263 11.353 11.868 10.632 10.266 11.485 11.569 ± ± i ± ± ± ± ± Table 11 : Known EBs 9.182 9.762 9.325 9.326 9.482 11.079 10.874 0.030 0.022 0.011 0.014 0.009 0.018 0.014 0.012 0.011 0.013 0.012 0.010 0.014 0 ± ± ± ± ± ± ± ± ± ± r ± ± ± Combined brightness 0.014 0.010 0.012 0.021 0.012 0.012 0.013 9.827 9.439 9.518 0 14.224 10.220 11.181 11.144 11.436 11.962 10.574 10.566 11.546 11.449 ± ± ± r ± ± ± ± Combined brightness 9.002 9.355 9.348 9.803 0 10.084 10.917 10.749 i 22 59 44 59 55 20 14 66 110 118 110 133 118 0 i 27 78 44 30 98 56 0 106 r 29 43 80 47 22 90 Table 10 : EB candidates with different catalogue classiﬁcation Data points 138 107 155 139 166 107 155 0 r 30 45 34 72 Data points 114 130 136 1.0492 1.0872 0.74342 0.80017 1.04128 0.791586 0.849457 0.896638 0.916856 0.953342 0.962812 0.982372 Period/d 1.0802672 0.90339 3.75807 1.891066 4.239372 5.530588 8.705443 9.552831 Period/d B B5 B9 B3 B0 B9 B7 ST B7V B4V: B2III B7IV B2/4 B1/2 B B3 B8 B9 ST B0II B2/5 B5/7II Name EQ Vel Name KY Pup BH Cen GU Mon V829 Car V380 Cen V724 Car HD 312137 CD-53 6259 CD-47 4546 HD 302532 HD 150792 HD 292711 HD 295557 CD-56 5767 CD-59 5583 TYC 8959-605-1 TYC 5987-657-1 TYC 6561-2119-1 2MASS J06412155-0108582 A.1 amplitudes and eccentricities 85 0 i 0.051 0.017 0.036 0.022 0.007 0.087 0.024 0.001 0.042 0.007 0.035 0.006 0.014 0.069 0.015 0.016 0.021 0.014 0.025 0.006 0.044 0.013 0.012 0.042 0.004 0.007 0.003 0.029 0.005 min e 0 – – r 0.069 0.029 0.004 0.072 0.031 0.024 0.001 0.003 0.014 0.074 0.010 0.040 0.060 0.042 0.021 0.014 0.000 0.006 0.044 0.019 0.043 0.010 0.009 0.007 0.028 0.105 0.005 0 i 0.532 0.489 0.523 0.514 0.504 0.555 0.515 0.501 0.527 0.504 0.522 0.504 0.491 0.456 0.490 0.510 0.514 0.509 0.484 0.496 0.472 0.492 0.508 0.473 0.502 0.495 0.498 0.519 0.503 1 D 0 – – r 0.456 0.518 0.497 0.546 0.519 0.515 0.499 0.502 0.509 0.547 0.494 0.475 0.462 0.527 0.514 0.509 0.500 0.496 0.472 0.488 0.527 0.493 0.494 0.504 0.482 0.433 0.503 0.083 0.018 0.019 0.025 0.015 0.019 0.032 0.015 0.026 0.027 0.127 0.032 0.016 0.021 0.028 0.021 0.022 0.016 0.028 0.025 0.032 0.020 0.018 0.018 0.014 0.019 0.017 0.017 0.021 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.422 0.098 0.113 0.262 0.087 0.291 0.427 0.146 0.188 0.276 0.239 0.271 0.294 0.382 0.210 0.121 0.443 0.234 0.279 0.409 0.313 0.113 0.083 0.137 0.159 0.269 0.461 0.115 0.409 /mag s A 0.043 0.020 0.025 0.021 0.023 0.022 0.024 0.021 0.024 0.057 0.029 0.021 0.023 0.020 0.024 0.019 0.024 0.022 0.023 0.020 0.028 0.024 0.024 0.022 0.017 0.018 0.027 0 – – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.371 0.103 0.254 0.100 0.281 0.436 0.163 0.181 0.234 0.240 0.263 0.311 0.388 0.137 0.431 0.253 0.281 0.413 0.312 0.093 0.094 0.143 0.163 0.271 0.456 0.079 0.419 0.092 0.018 0.020 0.025 0.015 0.019 0.034 0.015 0.026 0.029 0.132 0.034 0.016 0.021 0.027 0.021 0.022 0.017 0.028 0.025 0.032 0.021 0.018 0.019 0.015 0.020 0.018 0.017 0.021 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.663 0.332 0.236 0.327 0.122 0.485 0.564 0.156 0.279 0.737 0.360 0.487 0.431 0.699 0.299 0.134 0.710 0.367 0.295 0.475 0.409 0.500 0.086 0.231 0.277 0.352 0.490 0.392 0.479 /mag p A 0.045 0.020 0.025 0.021 0.023 0.023 0.024 0.021 0.025 0.059 0.029 0.021 0.024 0.020 0.024 0.019 0.024 0.022 0.023 0.020 0.028 0.023 0.024 0.022 0.017 0.018 0.027 0 – – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.524 0.238 0.341 0.134 0.684 0.599 0.169 0.271 0.757 0.336 0.473 0.455 0.683 0.148 0.741 0.378 0.286 0.495 0.388 0.511 0.115 0.241 0.300 0.368 0.493 0.412 0.497 0.038 0.011 0.015 0.014 0.013 0.071 0.015 0.011 0.015 0.014 0.012 0.010 0.010 0.016 0.008 0.010 0.008 0.009 0.010 0.016 0.012 0.009 0.022 0.010 0.010 0.008 0.010 0.009 0.012 0 ± ± ± ± ± ± ± ± ± ± ± ± i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 8.413 9.791 9.439 9.852 8.914 9.881 9.896 7.713 9.677 9.513 9.937 9.025 9.378 9.519 9.334 9.377 8.961 13.406 10.774 11.618 10.816 11.120 13.851 12.035 10.684 11.123 10.588 10.410 10.421 Known EBs, continued 0.020 0.012 0.011 0.011 0.014 0.029 0.016 0.011 0.014 0.011 0.011 0.012 0.015 0.012 0.013 0.014 0.011 0.014 0.014 0.010 0.013 0.015 0.013 0.013 0.009 0.010 0.017 0 ± ± ± ± ± ± ± ± ± ± ± ± – – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Combined brightness 9.756 9.329 9.826 8.717 9.832 9.735 9.544 9.328 9.882 8.888 9.176 9.695 9.255 9.276 8.857 13.570 10.685 11.704 10.733 10.996 13.980 11.964 10.646 11.509 10.554 10.342 10.369 0 i 98 44 25 45 34 22 61 99 66 27 50 45 46 78 49 24 30 52 99 65 39 106 164 110 160 111 106 110 136 0 – – r 45 32 53 57 29 69 30 53 51 72 29 36 94 42 Data points 137 130 139 104 128 192 112 109 137 109 160 153 128 1.485 1.594 1.10449 1.10886 1.20129 1.32776 1.36419 1.39942 1.53184 1.53546 1.114401 1.116572 1.127821 1.137587 1.166379 1.183494 1.250972 1.266288 1.275549 1.317723 1.417696 1.421472 1.480792 1.481179 1.516971 1.537911 1.540519 1.574437 1.600446 Period/d B9 B8 B8 B9 B4 B5 B7 B5 B9 B8 ST B5V B0V B3V B1V B3V B3III B5III B1III B8IV B1Vv B2IVe B9.5V B8/B9 B3/5II B8II/III B8III/IV B1V:nnp B1/2IIIn B3V+B5/7 Name LS 999 AI Cru HI Mon GM Car DW Car LV CMa HD 48934 HD 52504 HD 53339 HD 89714 V1288 Sco V1293 Sco V1331 Aql V1099 Cen HD 292396 HD 302617 HD 148420 HD 308588 HD 127980 HD 305687 HD 295427 HD 146526 HD 313508 BD-07 4674 CD-40 4427 TYC 8993-313-1 TYC 5125-3227-1 CoRoT 102842120 UCAC4 423-022168 86 A P P E N D I X A - TA B L E S 0 i 0.017 0.058 0.023 0.016 0.023 0.011 0.039 0.009 0.061 0.081 0.017 0.028 0.003 0.009 0.007 0.036 0.003 0.033 0.000 0.010 0.003 0.005 0.019 0.114 0.014 0.077 0.066 0.001 0.048 0.008 0.001 min e 0 r 0.002 0.019 0.012 0.006 0.004 0.011 0.039 0.029 0.012 0.081 0.002 0.060 0.009 0.009 0.046 0.095 0.005 0.020 0.011 0.028 0.004 0.008 0.004 0.057 0.074 0.004 0.066 0.006 0.048 0.017 0.013 0 i 0.489 0.537 0.485 0.510 0.486 0.493 0.525 0.505 0.539 0.552 0.489 0.482 0.502 0.494 0.504 0.523 0.502 0.521 0.500 0.506 0.498 0.503 0.512 0.573 0.509 0.549 0.542 0.501 0.531 0.505 0.499 1 D 0 r 0.499 0.488 0.493 0.504 0.502 0.493 0.525 0.482 0.508 0.552 0.501 0.538 0.506 0.506 0.529 0.560 0.503 0.487 0.507 0.482 0.503 0.495 0.497 0.464 0.453 0.498 0.542 0.496 0.531 0.511 0.508 0.021 0.048 0.017 0.026 0.048 0.024 0.020 0.024 0.021 0.025 0.022 0.021 0.020 0.018 0.084 0.017 0.020 0.018 0.014 0.091 0.020 0.015 0.018 0.028 0.025 0.032 0.017 0.019 0.023 0.019 0.044 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.390 0.472 0.138 0.781 0.291 0.166 0.099 0.261 0.113 0.206 0.133 0.174 0.365 0.381 0.219 0.092 0.469 0.214 0.134 0.414 0.301 0.106 0.065 0.126 0.199 0.115 0.216 0.361 0.215 0.109 0.190 /mag s A 0.020 0.033 0.024 0.026 0.036 0.021 0.020 0.023 0.022 0.025 0.027 0.021 0.024 0.033 0.047 0.019 0.020 0.022 0.020 0.057 0.020 0.018 0.021 0.019 0.025 0.026 0.020 0.018 0.032 0.021 0.028 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.419 0.518 0.138 0.810 0.247 0.175 0.113 0.273 0.113 0.195 0.127 0.176 0.320 0.373 0.210 0.074 0.513 0.220 0.131 0.344 0.309 0.082 0.052 0.117 0.186 0.131 0.223 0.353 0.202 0.158 0.152 0.021 0.052 0.017 0.026 0.055 0.025 0.020 0.025 0.021 0.026 0.022 0.021 0.020 0.019 0.091 0.017 0.020 0.018 0.014 0.101 0.020 0.015 0.018 0.028 0.025 0.034 0.018 0.019 0.023 0.019 0.053 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.415 0.853 0.181 0.803 0.705 0.378 0.131 0.381 0.208 0.468 0.201 0.276 0.697 0.613 0.433 0.170 0.644 0.221 0.140 0.663 0.307 0.292 0.269 0.233 0.211 0.412 0.335 0.655 0.319 0.174 0.696 /mag p A 0.020 0.035 0.024 0.027 0.038 0.021 0.020 0.023 0.022 0.025 0.027 0.020 0.024 0.033 0.051 0.019 0.020 0.022 0.020 0.064 0.020 0.018 0.021 0.019 0.025 0.026 0.020 0.018 0.031 0.021 0.031 0 r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.428 0.976 0.160 0.847 0.699 0.381 0.137 0.410 0.371 0.449 0.223 0.292 0.705 0.625 0.439 0.165 0.663 0.225 0.140 0.668 0.318 0.294 0.251 0.229 0.197 0.424 0.362 0.670 0.333 0.183 0.708 0.028 0.012 0.024 0.013 0.012 0.013 0.012 0.011 0.043 0.010 0.044 0.010 0.009 0.019 0.018 0.011 0.025 0.010 0.010 0.011 0.012 0.010 0.010 0.009 0.012 0.007 0.008 0.014 0.009 0.013 0.010 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± i ± ± ± ± ± ± ± ± ± ± ± ± ± ± 9.762 9.365 9.808 9.942 9.754 9.005 9.801 9.947 9.555 9.284 9.535 9.974 9.205 9.765 12.032 11.297 12.313 10.761 11.447 10.664 10.169 10.518 13.478 10.090 13.468 10.238 10.754 10.265 11.760 10.025 12.789 Known EBs, continued 0.019 0.015 0.022 0.011 0.013 0.015 0.011 0.025 0.012 0.030 0.011 0.011 0.010 0.014 0.011 0.015 0.010 0.014 0.011 0.012 0.017 0.013 0.023 0.010 0.010 0.011 0.010 0.014 0.010 0.019 0.011 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Combined brightness 9.570 9.335 9.677 9.969 9.977 9.604 8.957 9.859 9.720 9.425 9.118 9.395 9.909 9.106 9.672 12.232 11.265 12.446 10.549 11.369 10.617 10.655 13.703 10.197 13.871 10.072 10.729 10.419 11.901 10.005 13.023 0 i 47 63 66 28 26 43 24 24 52 34 72 24 99 31 99 63 78 65 37 45 30 99 44 57 125 118 149 186 114 136 100 0 r 85 83 69 32 30 45 31 31 39 27 53 68 49 43 34 43 Data points 164 155 109 102 129 171 215 163 129 112 112 153 129 109 112 1.9083 1.62591 1.62875 1.65269 1.68147 1.80734 1.82411 1.87593 1.632143 1.671001 1.685653 1.713243 1.786773 1.817019 1.862189 1.879844 1.881191 1.884768 1.886394 1.889891 1.893232 1.895402 1.896555 1.951677 2.006888 2.028815 2.036384 2.042323 2.043987 2.045343 2.072827 Period/d B B6 B8 B8 B4 B8 B5 B8 B0 B9 B1 B8 B3 B5 B5 B2 ST B5: B... B9V B0V B3V B5V B3V B6V B4IV B9.5V B3+B5 B8II/III B9III/IV B1/B2IV B1/3(V)nn Name LT Cen ET Cru ZZ Cru DV Car RZ Cen TU Nor GU Pup AO Mon V778 Sgr V714 Car V608 Cen V400 Nor HD 91849 HD 93482 HD 75872 HD 89538 HD 53317 V1223 Sco V560 Mon HD 322305 HD 314670 HD 328686 HD 111825 HD 326040 HD 295604 CD-27 4703 CD-52 7425 LS IV -14 73 CPD-56 2763 UCAC4 433-023565 2MASS J06490980-0424545 A.1 amplitudes and eccentricities 87 0 i 0.008 0.043 0.005 0.037 0.028 0.035 0.044 0.010 0.002 0.109 0.050 0.022 0.003 0.003 0.002 0.002 0.064 0.031 0.001 0.012 0.012 0.037 0.026 0.009 0.035 0.040 0.051 0.166 0.096 0.004 0.030 min e 0 – – – r 0.042 0.002 0.021 0.048 0.069 0.044 0.010 0.002 0.100 0.050 0.053 0.004 0.002 0.002 0.064 0.031 0.001 0.012 0.001 0.022 0.002 0.035 0.040 0.026 0.168 0.096 0.041 0.014 0 i 0.505 0.472 0.503 0.477 0.482 0.478 0.472 0.493 0.502 0.431 0.532 0.486 0.502 0.502 0.501 0.501 0.460 0.480 0.499 0.492 0.508 0.524 0.516 0.494 0.522 0.525 0.532 0.605 0.439 0.497 0.519 1 D 0 – – – r 0.527 0.499 0.487 0.470 0.456 0.472 0.493 0.502 0.436 0.532 0.534 0.502 0.501 0.501 0.540 0.480 0.501 0.492 0.500 0.514 0.501 0.522 0.525 0.516 0.607 0.439 0.474 0.509 0.052 0.021 0.025 0.023 0.021 0.021 0.018 0.019 0.023 0.022 0.025 0.024 0.019 0.021 0.019 0.077 0.027 0.015 0.021 0.021 0.020 0.024 0.021 0.015 0.050 0.020 0.025 0.018 0.028 0.019 0.025 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.599 0.219 0.127 0.234 0.211 0.111 0.389 0.071 0.360 0.152 0.101 0.119 0.435 0.506 0.169 0.730 0.322 0.242 0.370 0.317 0.424 0.171 0.375 0.448 0.329 0.257 0.134 0.341 0.476 0.413 0.328 /mag s A 0.030 0.021 0.036 0.025 0.021 0.025 0.024 0.028 0.025 0.026 0.024 0.027 0.023 0.039 0.028 0.022 0.024 0.025 0.020 0.024 0.020 0.032 0.028 0.022 0.020 0.028 0.026 0.022 0 – – – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.579 0.112 0.241 0.247 0.094 0.400 0.066 0.349 0.160 0.106 0.130 0.533 0.168 0.661 0.375 0.237 0.373 0.320 0.437 0.109 0.628 0.364 0.265 0.141 0.368 0.479 0.413 0.313 0.054 0.021 0.026 0.023 0.021 0.021 0.018 0.019 0.025 0.022 0.025 0.025 0.019 0.021 0.019 0.079 0.027 0.015 0.021 0.021 0.021 0.027 0.021 0.016 0.051 0.020 0.025 0.018 0.028 0.019 0.025 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.712 0.326 0.240 0.250 0.242 0.140 0.406 0.148 0.796 0.179 0.203 0.239 0.486 0.547 0.243 0.795 0.363 0.590 0.373 0.347 0.614 0.902 0.391 0.647 0.366 0.330 0.269 0.394 0.509 0.895 0.383 /mag p A 0.031 0.021 0.036 0.025 0.021 0.025 0.023 0.028 0.025 0.026 0.024 0.027 0.023 0.039 0.028 0.022 0.024 0.025 0.020 0.025 0.020 0.032 0.028 0.022 0.020 0.028 0.026 0.022 0 – – – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.711 0.239 0.272 0.255 0.147 0.422 0.144 0.813 0.200 0.208 0.246 0.581 0.259 0.729 0.377 0.613 0.381 0.368 0.613 0.920 0.684 0.427 0.359 0.282 0.423 0.524 0.931 0.431 0.024 0.012 0.013 0.012 0.012 0.014 0.014 0.034 0.015 0.010 0.014 0.028 0.013 0.010 0.015 0.014 0.013 0.012 0.010 0.010 0.012 0.012 0.011 0.010 0.008 0.011 0.012 0.012 0.008 0.010 0.010 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Known EBs, continued 8.823 9.958 9.205 9.577 9.998 7.981 9.550 9.248 9.600 9.733 9.224 8.356 9.345 9.839 9.449 12.421 10.783 11.683 10.122 10.574 10.535 11.277 12.909 10.937 10.993 10.719 12.494 10.863 10.132 10.633 10.232 0.014 0.011 0.012 0.018 0.016 0.014 0.019 0.017 0.011 0.015 0.017 0.012 0.011 0.016 0.012 0.022 0.015 0.015 0.013 0.014 0.017 0.012 0.012 0.013 0.015 0.010 0.018 0.015 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± – – – r ± ± ± ± ± ± ± ± ± ± ± ± ± Combined brightness 8.790 9.811 9.102 9.513 9.948 9.484 9.262 9.817 9.602 9.095 9.156 9.694 9.385 12.431 11.666 10.121 10.510 10.543 11.365 13.011 11.197 11.174 10.708 12.600 10.780 10.040 10.570 10.245 0 i 97 23 98 78 72 23 28 77 60 31 65 51 77 46 56 66 23 97 98 32 73 42 55 52 98 30 52 103 147 180 103 0 – – – r 31 32 40 94 83 51 58 69 24 34 44 80 36 83 Data points 108 129 113 106 111 107 107 111 108 130 212 109 129 107 2.31527 2.45288 2.87362 3.07012 2.094484 2.146238 2.158531 2.178634 2.185442 2.195854 2.207756 2.209566 2.227372 2.312495 2.332428 2.333288 2.428195 2.464128 2.473153 2.527596 2.541597 2.596996 2.752728 2.757736 2.853737 2.905347 2.956933 2.970734 3.025095 Period/d 2.4222338 2.9718631 B B2 B8 B8 B8 B3 B7 B2 B5 B8 B9 B0 ST B... B... B3V B2V B4V B8V B8V B5... B3:V B5III B1III B2III B9III B5/8 B5V(n) B7Ib/II B9II/III B5/B6V B6/B7V: Name HI Car CN Cir GP Car GL Car EN Car LZ Cen GV Nor AW Cru V417 Vel MM Cen V499 Sco V590 Sco V654 Car V733 Car ALS 9188 V745 Cen V450 Mon V882 Mon V521 Mon V1061 Cen HD 328701 HD 122792 HD 328219 HD 143605 HD 124671 HD 309036 HD 124237 HD 117259 HD 103223 HD 140275 TYC 5388-964-1 88 A P P E N D I X A - TA B L E S 0 i 0.057 0.011 0.021 0.104 0.035 0.006 0.140 0.006 0.002 0.029 0.049 0.013 0.004 0.031 0.017 0.025 0.070 0.013 0.015 0.064 0.110 0.024 0.019 0.451 0.084 0.079 0.029 0.012 0.014 0.014 0.071 min e 0 – r 0.057 0.008 0.021 0.097 0.057 0.015 0.025 0.007 0.015 0.078 0.049 0.066 0.004 0.035 0.017 0.008 0.068 0.015 0.041 0.053 0.110 0.044 0.020 0.449 0.084 0.058 0.028 0.014 0.025 0.104 0 i 0.536 0.493 0.513 0.434 0.478 0.496 0.411 0.496 0.501 0.519 0.531 0.492 0.502 0.480 0.489 0.484 0.544 0.509 0.509 0.541 0.570 0.485 0.512 0.777 0.553 0.450 0.481 0.493 0.491 0.509 0.545 1 D 0 – r 0.536 0.505 0.513 0.438 0.536 0.491 0.516 0.504 0.490 0.550 0.531 0.458 0.502 0.478 0.489 0.505 0.543 0.510 0.526 0.534 0.570 0.528 0.487 0.776 0.553 0.537 0.482 0.509 0.516 0.434 0.031 0.033 0.019 0.061 0.024 0.018 0.026 0.020 0.015 0.027 0.020 0.022 0.022 0.071 0.014 0.040 0.027 0.017 0.019 0.038 0.019 0.018 0.022 0.021 0.021 0.025 0.017 0.017 0.021 0.020 0.067 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.495 0.164 0.162 0.403 0.330 0.160 0.113 0.099 0.119 0.210 0.130 0.303 0.415 0.393 0.241 0.166 0.192 0.197 0.294 0.568 0.120 0.084 0.201 0.290 0.035 0.182 0.256 0.325 0.142 0.161 0.234 /mag s A 0.030 0.020 0.019 0.030 0.021 0.024 0.016 0.020 0.022 0.035 0.026 0.022 0.036 0.040 0.019 0.029 0.022 0.026 0.023 0.024 0.024 0.022 0.021 0.026 0.024 0.022 0.021 0.021 0.021 0.034 0 – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.498 0.152 0.173 0.390 0.333 0.229 0.175 0.083 0.122 0.209 0.131 0.320 0.426 0.314 0.249 0.136 0.195 0.199 0.261 0.578 0.110 0.101 0.215 0.288 0.041 0.184 0.262 0.309 0.095 0.240 0.033 0.034 0.020 0.062 0.024 0.018 0.027 0.020 0.015 0.027 0.021 0.022 0.023 0.073 0.014 0.048 0.028 0.017 0.019 0.039 0.019 0.018 0.022 0.021 0.022 0.025 0.017 0.018 0.026 0.020 0.068 0 i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.742 0.325 0.192 0.457 0.363 0.167 0.165 0.643 0.149 0.230 0.572 0.344 1.095 0.457 0.274 0.710 0.457 0.199 0.464 0.627 0.192 0.128 0.213 0.383 0.379 0.221 0.582 1.059 1.768 0.459 0.295 /mag p A 0.030 0.021 0.019 0.030 0.021 0.024 0.016 0.020 0.022 0.035 0.026 0.022 0.034 0.041 0.019 0.032 0.022 0.026 0.023 0.024 0.024 0.022 0.021 0.026 0.024 0.022 0.021 0.021 0.023 0.037 0 – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.758 0.337 0.195 0.422 0.358 0.259 0.409 0.678 0.157 0.276 0.609 0.370 1.139 0.434 0.259 0.743 0.469 0.207 0.470 0.640 0.186 0.124 0.234 0.353 0.401 0.241 0.610 1.123 2.110 0.537 0.019 0.018 0.031 0.013 0.019 0.011 0.012 0.031 0.022 0.016 0.017 0.011 0.011 0.009 0.013 0.040 0.011 0.010 0.011 0.008 0.019 0.013 0.007 0.010 0.011 0.010 0.010 0.013 0.016 0.009 0.011 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 9.427 9.953 9.388 8.988 9.091 8.782 9.972 9.122 9.518 9.286 9.902 9.774 9.481 9.446 8.535 11.021 12.079 12.898 10.450 10.801 10.206 10.042 13.299 12.019 10.305 11.876 10.326 10.301 10.453 10.016 12.890 Known EBs, continued 0.018 0.010 0.014 0.011 0.014 0.009 0.014 0.021 0.016 0.012 0.011 0.012 0.011 0.015 0.012 0.012 0.017 0.010 0.011 0.011 0.021 0.012 0.025 0.010 0.015 0.013 0.013 0.015 0.012 0.011 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± – r ± ± ± ± ± ± ± ± ± ± ± ± ± Combined brightness 9.376 9.301 8.941 9.084 9.965 8.577 9.780 9.170 9.789 9.240 9.910 9.602 9.459 11.245 12.040 12.930 10.425 10.637 10.733 10.166 13.353 12.488 10.225 11.999 10.049 10.150 10.199 10.787 10.093 13.120 0 i 27 57 56 12 94 24 51 47 47 45 30 47 61 51 57 29 52 38 36 54 19 110 110 171 137 110 156 157 103 135 134 0 – r 28 58 28 25 60 84 85 58 37 84 54 72 38 49 49 34 Data points 139 109 139 208 104 170 139 195 196 104 107 160 109 144 3.6932 4.4098 3.11003 3.90101 4.28415 4.51657 4.79772 4.94246 3.102353 3.128916 3.143934 3.192251 3.369419 3.399701 3.478149 3.523001 3.672074 3.683337 3.687099 3.773694 3.863783 3.913632 3.918012 3.920659 4.130738 4.310894 4.387334 4.587504 4.616741 4.670453 4.928896 Period/d B B3 B5 B8 B5 B8 B0 B8 B8 B5 B9 B8 B0 B3 B9 B3 ST B... B4V B9V B2III B7III B1III B2IV B4III: B9.5V B3/B4 B0.5III: B9III/IV B2III/IV B2/B3Ib/II B8/B9II/III Name AC Sct BN Cir BF Cen AE Cru TU Cru KT Cen WY Sgr VZ Cen DT Pup MR Cen LN Mus MQ Cen V611 Sco V607 Sco V713 Car V621 Cen HD 62607 V1216 Sco V863 Mon HD 305151 HD 151791 HD 124315 HD 316493 HD 303734 HD 303135 CD-29 4934 TYC 4799-220-1 TYC 8316-4368-1 GSC 05691-00334 2MASS J06415164-0037401 2MASS J06433732-0106283 A.1 amplitudes and eccentricities 89 0 – i 0.074 0.061 0.049 0.310 0.009 0.019 0.034 0.018 0.073 0.034 0.018 0.219 0.006 0.087 0.275 0.010 0.033 0.009 0.014 0.003 0.004 0.017 0.027 0.010 0.017 0.081 0.053 0.315 0.033 0.028 0.027 min e 0 – – – – r 0.047 0.095 0.027 0.020 0.290 0.019 0.037 0.032 0.034 0.018 0.248 0.006 0.077 0.242 0.012 0.018 0.002 0.014 0.041 0.004 0.041 0.010 0.014 0.053 0.315 0.033 0.026 0.013 0 – i 0.453 0.539 0.531 0.694 0.494 0.488 0.478 0.488 0.546 0.522 0.489 0.638 0.504 0.445 0.673 0.493 0.521 0.494 0.509 0.502 0.497 0.511 0.483 0.506 0.511 0.448 0.466 0.303 0.521 0.518 0.483 1 D 0 – – – – r 0.470 0.440 0.517 0.487 0.682 0.488 0.523 0.521 0.522 0.489 0.656 0.504 0.451 0.653 0.493 0.489 0.502 0.509 0.526 0.497 0.474 0.506 0.491 0.466 0.303 0.521 0.516 0.492 0.022 0.034 0.024 0.020 0.019 0.019 0.018 0.034 0.016 0.019 0.038 0.025 0.034 0.021 0.028 0.015 0.027 0.021 0.016 0.019 0.018 0.023 0.021 0.019 0.024 0.025 0.020 0.022 0.019 0.023 0.018 0 – i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.190 0.169 0.403 0.109 0.291 0.319 0.140 0.493 0.214 0.479 0.295 0.196 0.201 0.239 0.269 0.237 0.474 0.083 0.139 0.200 0.380 0.219 0.140 0.260 0.150 0.158 0.241 0.359 0.121 0.161 0.420 /mag s A 0.022 0.026 0.019 0.026 0.023 0.025 0.030 0.022 0.024 0.038 0.043 0.026 0.023 0.025 0.026 0.023 0.020 0.021 0.024 0.029 0.021 0.023 0.021 0.025 0.026 0.024 0.025 0.027 0 – – – – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.191 0.207 0.248 0.472 0.132 0.301 0.145 0.390 0.470 0.295 0.229 0.123 0.249 0.170 0.234 0.471 0.072 0.180 0.203 0.378 0.137 0.252 0.111 0.244 0.350 0.120 0.140 0.373 0.022 0.035 0.024 0.021 0.019 0.019 0.018 0.035 0.016 0.019 0.042 0.025 0.036 0.021 0.028 0.015 0.028 0.021 0.016 0.019 0.018 0.023 0.021 0.019 0.027 0.024 0.020 0.022 0.020 0.023 0.018 0 – i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.235 0.644 0.693 0.281 0.337 0.343 0.149 0.620 0.247 0.505 0.782 0.286 0.354 0.261 0.329 0.281 0.831 0.320 0.226 0.575 0.709 0.659 0.206 0.349 0.954 0.274 0.255 0.367 0.350 0.316 0.498 /mag p A 0.022 0.026 0.019 0.026 0.023 0.025 0.030 0.022 0.024 0.042 0.041 0.027 0.023 0.025 0.026 0.023 0.020 0.021 0.024 0.029 0.021 0.023 0.023 0.025 0.026 0.024 0.025 0.026 0 – – – – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.241 0.634 0.669 0.698 0.299 0.331 0.164 0.587 0.523 0.782 0.292 0.389 0.275 0.358 0.284 0.893 0.325 0.236 0.696 0.735 0.205 0.350 1.056 0.261 0.366 0.311 0.382 0.734 0.026 0.022 0.022 0.017 0.014 0.008 0.011 0.013 0.010 0.012 0.011 0.014 0.013 0.011 0.011 0.010 0.010 0.010 0.011 0.016 0.012 0.007 0.018 0.011 0.011 0.009 0.016 0.011 0.015 0.014 0.010 0 ± ± ± ± ± ± ± ± ± ± ± – i ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 9.011 9.367 9.259 8.573 9.891 8.972 8.616 9.177 8.734 9.318 8.912 9.773 9.876 9.235 9.364 8.321 9.799 7.936 8.674 8.716 10.275 10.632 12.720 12.042 10.906 10.146 10.454 11.150 10.304 10.100 10.074 Known EBs, continued 0.017 0.010 0.012 0.022 0.013 0.016 0.011 0.013 0.011 0.013 0.015 0.013 0.012 0.015 0.013 0.014 0.017 0.012 0.027 0.013 0.016 0.013 0.010 0.014 0.017 0.012 0.016 0.016 0 ± ± ± ± ± ± ± ± ± ± ± ± – – – – r ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Combined brightness 9.362 9.938 9.221 9.870 8.940 9.493 8.533 9.810 8.722 9.849 9.851 9.588 9.967 9.680 8.711 8.975 10.500 10.528 10.766 12.720 12.209 11.117 10.030 10.396 11.437 10.167 10.007 10.041 0 – i 38 17 44 52 52 52 84 32 46 24 34 46 55 47 25 34 84 98 25 65 22 85 60 31 57 103 101 180 186 124 128 0 – – – – r 44 41 36 42 83 92 45 84 25 39 71 56 85 38 39 93 29 68 90 37 58 Data points 107 101 109 215 144 107 166 7.578 74.64 12.579 15.493 19.811 32.998 5.38322 7.92908 10.2703 4.952648 4.953633 5.193068 5.358612 5.562018 5.860055 5.866478 5.921197 5.954658 5.978884 6.038942 6.321659 6.354527 8.191871 8.532968 9.657717 9.817036 10.60279 Period/d 11.111285 11.597675 13.228079 14.332623 32.454896 B B B B9 B6 B0 B8 B2 B6 B9 B8 B5 B9 B3 B8 B9 ST B... B5:... B1III B9III B3III B1III B9IV B1Iab Bp sh B5/7Ib B3/5III B1:V:pe B1III(n) B6II/III B2II/III B3n+B0 W Sct Name CS Cir CT Sct CZ Vel LP Ara EQ Cru KU Car UW Cru MO Cen V493 Sct AU Mon V565 Sco V348 Car V674 Car V885 Aql V877 Cen V346 Cen V878 Cen HD 96609 HD 94187 HD 84511 HD 97726 V925 Mon V1153 Cen HD 306096 HD 124289 HD 312051 HD 299953 BD-11 4667 BD-14 5043 CD-35 4659 2MASS J08444397-4305239 90 A P P E N D I X A - TA B L E S

A.2CALCULATEDSPECTRALTYPES

The number of measurements for each ﬁlter are given in the corresponding # columns.

Table 12: Calculated spectral types for the new EB candidates

Name SIMBAD ST calc. ST U #U B #B V #V BD-03 4416 B O5 11.14 ± 0.072 8 11.47 ± 0.073 8 10.459 ± 0.05 6

BD-02 4797 B O5 11.303 ± 0.074 8 11.549 ± 0.046 8 10.606 ± 0.049 6

BD-17 5191s B O6 11.042 ± 0.033 37 11.387 ± 0.031 53 10.627 ± 0.025 50

HD 300814 B3 B0 9.199 ± 0.08 11 9.715 ± 0.046 8 9.287 ± 0.035 8

HD 300777 B2 B0 9.19 ± 0.061 8 9.728 ± 0.041 5 9.349 ± 0.033 5

CPD-59 5411 B B0 11.296 ± 0.092 5 11.574 ± 0.034 9 10.843 ± 0.028 8

HD 168862 B3II B0 9.27 ± 0.082 40 9.809 ± 0.07 53 9.401 ± 0.074 57

HD 323068 B B0.5 11.248 ± 0.159 3 11.432 ± 0.115 4 10.656 ± 0.12 4

TYC 5699-3842-1 B5 B0.5 11.431 ± 0.122 3 11.727 ± 0.046 13 11.089 ± 0.029 9

TYC 5125-2757-1 B B0.5 10.788 ± 0.113 3 11.447 ± 0.032 11 11.268 ± 0.032 8

LS IV -11 22 B... B0.5 11.843 ± 0.129 6 12.066 ± 0.038 26 11.317 ± 0.041 18

CPD-59 2618 B1.5V B0.5 11.632 ± 0.076 8 12.149 ± 0.14 4 11.786 ± 0.106 4

HD 305842 B5 B0.5 9.982 ± 0.075 10 10.605 ± 0.056 3 10.384 ± 0.06 3

LS IV -06 20 B B0.5 10.855 ± 0.114 3 11.371 ± 0.034 11 10.977 ± 0.029 8

HD 302981 B3 B1 9.991 ± 0.065 8 10.554 ± 0.043 5 10.303 ± 0.034 5

CD-59 5281 B B1 10.52 ± 0.064 9 10.948 ± 0.045 10 10.5 ± 0.041 9

2MASS J06401339-0114484 B3III B1.5 13.389 ± 0.15 12 13.707 ± 0.045 11 13.179 ± 0.047 12

TYC 5385-1027-1 B2 B1.5 11.208 ± 0.061 11 11.46 ± 0.029 13 10.908 ± 0.025 12

HD 300349 B1/3 B1.5 10.246 ± 0.107 3 10.659 ± 0.056 3 10.293 ± 0.043 3

TYC 9011-1728-1 B0 B1.5 11.986 ± 0.1 6 12.283 ± 0.078 14 11.768 ± 0.095 14

HD 150723 B8 B1.5 9.369 ± 0.05 12 9.753 ± 0.026 12 9.336 ± 0.021 12

HD 322453 B8 B1.5 8.965 ± 0.087 4 9.525 ± 0.04 5 9.305 ± 0.026 7

CD-51 9509 B8 B2 11.815 ± 0.083 7 11.984 ± 0.045 14 11.406 ± 0.047 15

HD 322270 B5 B2 10.156 ± 0.098 9 10.605 ± 0.044 13 10.348 ± 0.063 14

TYC 4799-714-1 B2IV B2 11.93 ± 0.068 12 12.276 ± 0.035 11 11.885 ± 0.027 12

HD 62869 B(5) B2 9.846 ± 0.09 4 10.304 ± 0.047 4 10.107 ± 0.037 4

TYC 8319-650-1 B... B2 12.798 ± 0.109 8 12.774 ± 0.065 7 11.931 ± 0.068 7

GSC 05692-01147 B7 B2 12.645 ± 0.147 3 12.935 ± 0.059 11 12.476 ± 0.067 8

TYC 8995-2720-1 B8 B2.5 11.711 ± 0.108 4 12.016 ± 0.117 6 11.67 ± 0.126 6

HD 140823 B8/9II/III B2.5 9.976 ± 0.069 7 10.332 ± 0.024 14 10.03 ± 0.02 14

HD 326476 B9 B2.5 10.5 ± 0.19 4 10.791 ± 0.042 5 10.453 ± 0.029 7

HD 326704 B9 B2.5 11.014 ± 0.09 5 11.27 ± 0.071 5 10.829 ± 0.04 4

CD-26 4800 B4/B5 B2.5 11.274 ± 0.114 4 11.636 ± 0.077 4 11.366 ± 0.078 4

UCAC2 5319779 B5 B2.5 11.908 ± 0.122 9 12.202 ± 0.054 4 11.863 ± 0.047 4

HD 306429 B8 B2.5 10.883 ± 0.066 9 11.253 ± 0.051 4 10.986 ± 0.05 4

HD 146629 B5/8IV/V B2.5 10.422 ± 0.067 8 10.766 ± 0.103 7 10.47 ± 0.1 7

HD 316017 B3 B2.5 11.136 ± 0.116 3 11.29 ± 0.074 2 10.766 ± 0.047 3

CD-51 10244 B8 B3 10.616 ± 0.079 6 10.921 ± 0.034 8 10.631 ± 0.032 7

HD 326732 B9 B3 12.307 ± 0.088 7 12.399 ± 0.048 6 11.824 ± 0.042 5

HD 306392 B8 B3 10.9 ± 0.066 9 11.284 ± 0.049 4 11.079 ± 0.042 4

HD 328533 B9 B3.5 10.72 ± 0.056 12 11.023 ± 0.028 12 10.74 ± 0.024 12

HD 60366 B9III B3.5 10.018 ± 0.061 9 10.353 ± 0.046 8 10.113 ± 0.048 8

CD-52 7093 B9 B3.5 10.29 ± 0.062 9 10.577 ± 0.05 9 10.283 ± 0.049 9 A.2 calculated spectral types 91

Calculated spectral types for the new EB candidates, continued

Name SIMBAD ST calc. ST U #U B #B V #V TYC 4805-1594-1 B3: B4 11.216 ± 0.103 4 11.574 ± 0.041 7 11.379 ± 0.033 7

CD-24 5898A B9 B4 9.006 ± 0.07 16 9.539 ± 0.049 10 9.591 ± 0.034 10

HD 304241 B8 B4 9.896 ± 0.064 8 10.315 ± 0.149 3 10.213 ± 0.142 3

CCDM J16349-5242AB B8/9V B4.5 9.349 ± 0.071 6 9.743 ± 0.051 8 9.633 ± 0.055 7

HD 306140 B9 B4.5 9.821 ± 0.064 8 10.113 ± 0.231 3 9.866 ± 0.227 3

CCDM J06493-0239AB B9IV/V B5 9.696 ± 0.09 4 9.979 ± 0.038 7 9.783 ± 0.043 7

HD 66647 B9IV/V B5 9.939 ± 0.081 5 10.259 ± 0.047 4 10.061 ± 0.037 4

HD 308648 B B5 11.18 ± 0.103 4 11.471 ± 0.085 2 11.268 ± 0.095 2

HD 146292 B8/9III B5 10.351 ± 0.066 8 10.696 ± 0.037 7 10.53 ± 0.029 7

HD 306745 B8 B6 10.418 ± 0.095 4 10.719 ± 0.07 2 10.578 ± 0.055 2

CPD-26 2634 B9III B6 11.221 ± 0.117 3 11.479 ± 0.061 3 11.325 ± 0.049 3

HD 292370 B8 B6 11.239 ± 0.103 4 11.464 ± 0.043 6 11.254 ± 0.035 6

HD 54436 B9V B7 8.986 ± 0.076 5 9.347 ± 0.031 8 9.346 ± 0.024 8

HD 53542 B9/A0V B7.5 9.256 ± 0.086 7 9.506 ± 0.125 9 9.41 ± 0.115 9

HD 295887 B9 B8 10.559 ± 0.081 119 10.69 ± 0.039 134 10.524 ± 0.036 137

Table 13: Calculated spectral types for the EB candidates of different catalogue classiﬁcation

Name SIMBAD ST calc. ST U #U B #B V #V CD-59 5583 B0II O5 10.554 ± 0.086 5 10.919 ± 0.029 14 10.093 ± 0.029 14

CD-56 5767 B O7 11.255 ± 0.092 5 11.457 ± 0.037 7 10.537 ± 0.029 7

HD 302532 B3 B0 9.166 ± 0.1 3 9.727 ± 0.053 3 9.334 ± 0.04 3

HD 150792 B5/7II B1.5 9.383 ± 0.058 9 9.847 ± 0.04 11 9.53 ± 0.041 10

HD 171223 B9II B1.5 8.865 ± 0.113 3 9.387 ± 0.032 11 9.177 ± 0.041 8

HD 295557 B9 B5 10.438 ± 0.095 8 10.826 ± 0.038 7 10.756 ± 0.035 13

HD 292711 B8 B7 10.729 ± 0.098 4 10.995 ± 0.041 6 10.884 ± 0.033 6 92 A P P E N D I X A - TA B L E S

Table 14: Calculated spectral types for the known EBs

Name SIMBAD ST calc. ST U #U B #B V #V BD-11 4667 B1:V:pe O5 10.22 ± 0.116 3 10.552 ± 0.065 13 9.715 ± 0.074 9

BD-14 5043 B O5 11.048 ± 0.099 21 11.272 ± 0.09 25 10.239 ± 0.083 19

W Sct B3n+B0 O8 10.413 ± 0.153 21 10.71 ± 0.07 25 9.925 ± 0.074 19

CD-47 4546 B1/2 O9.5 11.543 ± 0.124 3 11.782 ± 0.063 3 10.962 ± 0.047 3

V1153 Cen B O9.5 10.345 ± 0.093 5 10.581 ± 0.094 10 9.777 ± 0.095 9

TYC 8316-4368-1 B... O9.5 12.634 ± 0.211 10 12.557 ± 0.119 9 11.363 ± 0.105 11

GSC 05691-00334 B3 O9.5 11.564 ± 0.393 4 11.863 ± 0.133 13 11.116 ± 0.156 9

V607 Sco B8 O9.5 10.157 ± 0.273 4 10.604 ± 0.201 4 10.052 ± 0.153 6

CPD-56 2763 B... B0 10.891 ± 0.114 3 11.279 ± 0.06 3 10.688 ± 0.045 3

HD 302617 B8 B0 9.342 ± 0.101 3 9.968 ± 0.054 3 9.683 ± 0.052 3

V878 Cen B1III B0 11.91 ± 0.22 6 11.779 ± 0.219 10 10.564 ± 0.211 9

V608 Cen B6 B0 13.056 ± 0.301 4 13.316 ± 0.212 6 12.593 ± 0.175 6

V1216 Sco B0 B0 10.728 ± 0.198 6 11.001 ± 0.153 8 10.268 ± 0.152 8

CT Sct B9 B0 10.367 ± 0.123 3 10.932 ± 0.103 9 10.582 ± 0.093 7

V674 Car B8 B0 9.731 ± 0.057 10 10.402 ± 0.055 3 10.178 ± 0.047 3

LS IV -14 73 B B0 10.773 ± 0.089 21 11.256 ± 0.081 25 10.773 ± 0.088 19

GU Mon B2III B0.5 11.546 ± 0.23 12 12.067 ± 0.266 11 11.68 ± 0.27 12

CZ Vel B6 B0.5 11.515 ± 0.146 4 11.702 ± 0.124 4 10.908 ± 0.146 4

V713 Car B2III B0.5 9.228 ± 0.061 8 9.814 ± 0.06 5 9.537 ± 0.064 5

V714 Car B2 B0.5 9.403 ± 0.062 8 10.025 ± 0.042 5 9.814 ± 0.032 5

GP Car B2 B0.5 11.933 ± 0.116 13 12.208 ± 0.144 8 11.526 ± 0.141 8

HD 328686 B0 B0.5 10.655 ± 0.069 12 11.032 ± 0.111 12 10.511 ± 0.108 12

HD 151791 B2/B3Ib/II B0.5 9.288 ± 0.073 6 9.78 ± 0.064 8 9.371 ± 0.028 6

HD 316493 B5 B0.5 10.414 ± 0.094 4 10.747 ± 0.041 6 10.16 ± 0.028 7

AC Sct B9 B0.5 9.932 ± 2.135 3 10.507 ± 0.03 10 10.2 ± 0.039 8

HD 146526 B8IV B1 8.373 ± 0.062 7 9.014 ± 0.04 8 8.851 ± 0.036 9

CD-40 4427 B1V B1 10.205 ± 0.137 5 10.549 ± 0.121 5 10.027 ± 0.114 5

HD 303135 B0 B1 9.854 ± 0.083 8 10.278 ± 0.216 4 9.831 ± 0.216 4

V733 Car B B1 10.523 ± 0.068 8 11.057 ± 0.186 4 10.791 ± 0.178 4

DW Car B1III B1 8.874 ± 0.119 2 9.589 ± 0.201 3 9.514 ± 0.203 3

HD 326040 B3 B1 10.003 ± 0.061 9 10.506 ± 0.029 11 10.159 ± 0.024 10

HD 328701 B8 B1 11.482 ± 0.128 9 11.802 ± 0.123 9 11.251 ± 0.126 7

GL Car B3:V B1 9.133 ± 0.129 9 9.656 ± 0.045 4 9.385 ± 0.035 4

CD-35 4659 B... B1.5 9.976 ± 0.128 2 10.492 ± 0.068 2 10.222 ± 0.053 2

LN Mus B1III B1.5 9.058 ± 0.098 3 9.534 ± 0.063 2 9.278 ± 0.076 2

HD 314670 B8 B1.5 9.962 ± 0.091 4 10.359 ± 0.075 6 9.929 ± 0.068 7

2MASS J06415164-0037401 B2IV B1.5 12.938 ± 0.145 12 13.35 ± 0.042 11 13.016 ± 0.09 12

HD 48934 B8 B1.5 8.839 ± 0.051 12 9.42 ± 0.027 11 9.301 ± 0.028 12

TYC 5388-964-1 B... B1.5 11.891 ± 0.083 11 12.183 ± 0.082 13 11.684 ± 0.079 12

TYC 5987-657-1 B B1.5 12.4 ± 0.158 9 12.696 ± 0.148 8 12.201 ± 0.158 8

CD-29 4934 B3/B4 B1.5 10.379 ± 0.084 5 10.903 ± 0.052 5 10.681 ± 0.053 5

CD-27 4703 B0V B1.5 11.48 ± 0.189 3 11.978 ± 0.136 3 11.738 ± 0.132 3

KU Car B8 B1.5 11.032 ± 0.242 8 11.408 ± 0.149 4 10.954 ± 0.145 4 A.2 calculated spectral types 93

Calculated spectral types for the known EBs, continued

Name SIMBAD ST calc. ST U #U B #B V #V HD 306096 B0 B1.5 8.901 ± 0.056 9 9.391 ± 0.14 4 9.129 ± 0.142 4

AI Cru B2IVe B1.5 9.257 ± 0.237 4 9.861 ± 0.246 4 9.767 ± 0.203 4

ZZ Cru B3V B1.5 9.26 ± 0.107 7 9.875 ± 0.079 5 9.77 ± 0.078 5

RZ Cen B1/B2IV B1.5 8.879 ± 0.253 5 9.466 ± 0.32 8 9.332 ± 0.221 7

V1293 Sco B0V B1.5 9.632 ± 0.191 4 10.135 ± 0.09 5 9.902 ± 0.075 7

HD 322305 B8 B1.5 9.171 ± 0.172 4 9.67 ± 0.064 5 9.426 ± 0.066 7

HD 313508 B8 B1.5 10.328 ± 0.131 4 10.75 ± 0.258 2 10.369 ± 0.152 4

DV Car B8 B1.5 9.631 ± 0.126 2 10.307 ± 0.055 3 10.286 ± 0.044 3

HD 309036 B3 B2 10.392 ± 0.134 2 10.814 ± 0.101 6 10.495 ± 0.092 6

V560 Mon B6V B2 13.723 ± 0.22 12 13.886 ± 0.27 11 13.258 ± 0.243 12

V450 Mon B5... B2 11.876 ± 0.209 4 12.067 ± 0.143 6 11.521 ± 0.145 6

HI Mon B3/5II B2 8.999 ± 0.087 4 9.486 ± 0.135 7 9.316 ± 0.121 7

HD 52504 B1V:nnp B2 8.768 ± 0.086 6 9.373 ± 0.089 9 9.366 ± 0.094 9

LS 999 B3V+B5/7 B2 11.97 ± 0.18 5 12.418 ± 0.163 4 12.154 ± 0.159 4

2MASS J08444397-4305239 B5:... B2 12.568 ± 0.145 3 12.62 ± 0.071 3 11.879 ± 0.054 3

HD 305151 B B2 10.246 ± 0.134 13 10.734 ± 0.144 8 10.504 ± 0.129 8

HI Car B8 B2 10.568 ± 0.258 10 11.008 ± 0.065 3 10.725 ± 0.072 3

EN Car B0 B2 10.113 ± 0.134 9 10.504 ± 0.047 4 10.161 ± 0.037 4

TU Cru B3 B2 11.821 ± 0.215 4 11.963 ± 0.215 3 11.339 ± 0.176 4

V745 Cen B7Ib/II B2 9.156 ± 0.136 5 9.658 ± 0.258 13 9.454 ± 0.235 14

CS Cir B6II/III B2 8.82 ± 0.069 6 9.23 ± 0.024 13 8.969 ± 0.04 14

HD 143605 B3V B2 8.755 ± 0.075 5 9.258 ± 0.195 6 9.08 ± 0.193 6

HD 148420 B8III/IV B2 9.913 ± 0.241 9 10.345 ± 0.203 11 10.05 ± 0.197 11

V400 Nor B5 B2 10.167 ± 0.081 8 10.507 ± 0.055 10 10.158 ± 0.06 9

CD-52 7425 B5: B2 10.603 ± 0.151 6 11.015 ± 0.16 8 10.729 ± 0.16 7

V590 Sco B5 B2 10.536 ± 0.113 4 10.696 ± 0.044 5 10.107 ± 0.032 7

WY Sgr B4III: B2 9.436 ± 0.191 4 9.81 ± 0.065 2 9.514 ± 0.255 4

TYC 5125-3227-1 B9 B2 11.903 ± 0.142 3 12.243 ± 0.201 11 11.838 ± 0.221 8

BD-07 4674 B7 B2 10.538 ± 0.11 3 10.953 ± 0.051 11 10.688 ± 0.058 8

HD 94187 B3/5III B2 9.125 ± 0.122 2 9.655 ± 0.098 3 9.525 ± 0.097 3

HD 305687 B5 B2 9.603 ± 0.231 2 10.043 ± 0.137 3 9.802 ± 0.138 3

GV Nor B5/8 B2 10.363 ± 0.071 7 10.789 ± 0.035 8 10.491 ± 0.026 9

V565 Sco B3 B2 10.126 ± 0.092 4 10.633 ± 0.042 5 10.446 ± 0.029 7

V1223 Sco B1 B2 10.54 ± 0.104 9 11.036 ± 0.038 13 10.824 ± 0.03 14

TYC 4799-220-1 B4V B2.5 11.89 ± 0.065 12 12.289 ± 0.035 11 12.04 ± 0.029 12

HD 295604 B5 B2.5 9.518 ± 0.088 4 10.012 ± 0.036 7 9.933 ± 0.039 7

UCAC4 433-023565 B5V B2.5 14.63 ± 0.188 4 14.691 ± 0.069 7 14.034 ± 0.055 7

KY Pup B2/4 B2.5 11.439 ± 0.33 3 11.89 ± 0.282 3 11.738 ± 0.275 3

TYC 6561-2119-1 B7V B2.5 11.837 ± 0.126 3 12.118 ± 0.065 3 11.744 ± 0.052 3

HD 75872 B4IV B2.5 9.164 ± 0.1 3 9.654 ± 0.053 3 9.531 ± 0.041 3

V417 Vel B8 B2.5 10.712 ± 0.181 3 11.079 ± 0.133 3 10.804 ± 0.126 3

HD 91849 B8II/III B2.5 9.231 ± 0.1 3 9.707 ± 0.062 3 9.564 ± 0.059 3

HD 122792 B6/B7V: B2.5 9.445 ± 0.072 6 9.934 ± 0.05 8 9.796 ± 0.049 7 94 A P P E N D I X A - TA B L E S

Calculated spectral types for the known EBs, continued

Name SIMBAD ST calc. ST U #U B #B V #V V621 Cen B8/B9II/III B2.5 10.021 ± 0.129 2 10.41 ± 0.175 11 10.193 ± 0.159 12

LP Ara B8 B2.5 10.266 ± 0.303 12 10.554 ± 0.09 12 10.199 ± 0.228 12

HD 53339 B3V B2.5 9.089 ± 0.106 11 9.548 ± 0.146 13 9.389 ± 0.144 12

HD 117259 B5V(n) B2.5 9.115 ± 0.07 6 9.629 ± 0.148 9 9.536 ± 0.121 8

BN Cir B9III/IV B2.5 9.78 ± 0.08 5 10.255 ± 0.024 14 10.111 ± 0.02 14

HD 299953 B9 B3 9.606 ± 0.049 13 10.046 ± 0.029 10 9.935 ± 0.021 12

MO Cen B5 B3 9.697 ± 0.09 4 10.034 ± 0.066 2 9.774 ± 0.051 2

MQ Cen B5 B3 9.763 ± 0.194 4 10.12 ± 0.067 2 9.899 ± 0.052 2

V1099 Cen B5 B3 10.8 ± 0.098 4 11.214 ± 0.403 3 11.053 ± 0.388 3

HD 127980 B8/B9 B3 10.414 ± 0.12 6 10.777 ± 0.077 14 10.542 ± 0.07 14

HD 308588 B4 B3 10.384 ± 0.099 4 10.778 ± 0.07 5 10.597 ± 0.079 5

HD 328219 B8 B3 10.35 ± 0.064 9 10.614 ± 0.053 11 10.244 ± 0.048 11

HD 97726 B9 B3.5 9.487 ± 0.062 8 9.661 ± 0.184 3 9.213 ± 0.244 3

HD 93482 B9III/IV B3.5 9.504 ± 0.062 8 9.97 ± 0.165 4 9.902 ± 0.162 4

AO Mon B3+B5 B4 9.199 ± 0.077 5 9.68 ± 0.03 9 9.66 ± 0.024 9

GU Pup B8 B4 11.557 ± 0.269 4 11.797 ± 0.245 4 11.459 ± 0.238 4

V380 Cen B4V: B4 9.336 ± 0.116 4 9.786 ± 0.224 6 9.715 ± 0.187 6

HD 124671 B9II/III B4 9.823 ± 0.081 5 10.162 ± 0.044 13 9.944 ± 0.043 14

2MASS J06433732-0106283 B9V B4.5 13.64 ± 0.128 12 13.833 ± 0.057 11 13.458 ± 0.054 12

HD 140275 B9III B4.5 9.402 ± 0.055 10 9.801 ± 0.104 12 9.679 ± 0.091 14

UW Cru B6 B5 13.365 ± 0.2 2 13.302 ± 0.162 2 12.625 ± 0.209 2

HD 292396 B9 B5 10.514 ± 0.096 4 10.836 ± 0.041 6 10.695 ± 0.035 6

ALS 9188 B... B5 11.814 ± 0.112 4 12.049 ± 0.047 6 11.77 ± 0.038 6

HD 53317 B9 B5 8.718 ± 0.114 6 9.149 ± 0.095 9 9.133 ± 0.096 9

V882 Mon B8V B5 8.707 ± 0.102 120 9.116 ± 0.069 137 9.059 ± 0.091 130

DT Pup B3 B5 14.449 ± 0.186 8 14.325 ± 0.093 8 13.557 ± 0.136 8

TYC 8959-605-1 B9 B5 11.537 ± 0.159 10 11.738 ± 0.386 3 11.379 ± 0.38 3

KT Cen B8 B5 12.353 ± 0.38 4 12.448 ± 0.385 3 11.989 ± 0.393 3

AW Cru B7 B5 13.722 ± 0.263 4 13.791 ± 0.141 4 13.284 ± 0.186 4

HD 124289 B9III B5 9.828 ± 0.105 7 10.117 ± 0.048 10 9.877 ± 0.034 25

V778 Sgr B8 B5 12.44 ± 0.122 4 12.526 ± 0.085 2 12.05 ± 0.143 4

BH Cen B5 B6 10.413 ± 0.383 4 10.679 ± 0.426 5 10.467 ± 0.408 5

HD 295427 B9 B6 10.225 ± 0.094 4 10.511 ± 0.04 6 10.389 ± 0.031 6

V521 Mon B9 B6 9.946 ± 0.162 4 10.229 ± 0.161 6 10.085 ± 0.149 6

HD 89538 B9.5V B6 9.828 ± 0.171 5 10.173 ± 0.129 3 10.08 ± 0.122 3

MM Cen B2 B6 12.733 ± 0.28 15 12.81 ± 0.231 13 12.392 ± 0.218 14

TU Nor B4 B6 13.237 ± 0.124 5 13.216 ± 0.279 6 12.652 ± 0.254 6

HD 62607 B9.5V B7 9.498 ± 0.088 4 9.8 ± 0.046 4 9.732 ± 0.036 4

HD 303734 B9 B7 10.046 ± 0.075 6 10.279 ± 0.062 6 10.108 ± 0.062 6

EQ Vel B7 B8 11.646 ± 0.124 3 11.746 ± 0.062 3 11.543 ± 0.051 3

CD-53 6259 B9 B8 10.859 ± 0.179 10 10.936 ± 0.124 12 10.707 ± 0.171 14 B APPENDIXB-CONCEPTSAND METHODS

B.1ORBITALELEMENTS

In order to fully describe an object’s orbit and its position on it at a given time, a set of six parameters is needed, the orbital elements. The speciﬁc selection of these depends on the problem at hand, but there are always two parameters describing the orbits’ orientation with respect to a reference plane and direction, two parameters describing the shape and size of the orbit and two parameters for describing the orientation of the orbit within its plane and the position of the body on its orbit at a given time. In corresponding order, the traditional set of the so-called Keplerian or classical orbital elements consists of the inclination i, the longitude of the ascending node Ω, the eccentricity e, semi-major axis a, the argument of periapsis ω and the mean anomaly at 1 epoch t0, M0 . Illustrations are given in Figures 64 and 65.

Figure 64: Ellipse parameters. F, F’=focal points, a=semi-major axis, b=semi-minor axis, e=eccentricity.2

1 In the case of a circular orbit, the radius is used instead of the semi-major axis and ω is often arbitrarily placed at the ascending node, i.e. ω = 0. 2 Adapted from https://quantumredpill.ﬁles.wordpress.com/2013/01/ellipse.png.

95 96 APPENDIXB-CONCEPTSANDMETHODS

Figure 65: Orbit orientation with respect to reference plane.3

Shown in Figure 65 is the true anomaly ν, i.e. the angular distance of the object’s orbital position to the periapsis point, measured from the corresponding focus, i.e. the centre of mass (see also Figure 66). The mean anomaly is the angular distance from the periapsis point which the object would have if it moved in a circular orbit (the centre being the centre of the ellipse) with constant speed and same orbital period as the

actual body. The eccentric anomaly E0 used in Chapter 4 can be seen as a link between these two anomalies. It is related to the mean anomaly via Kepler’s equation

M0 = E0 − e sinE0 (15)

It is also related to the true anomaly ν via

e + cosν0 cosE0 = (16) 1 + e cosν0

x2 y2 which can be derived from Figure 66 using the ellipse equation 2 + 2 = 1 together a b q b 2 with basic trigonometric relations and the deﬁnition of the eccentricity, e = 1 − ( a ) . For an EB, if the observer’s line of sight is parallel to the minor axis, then ν = 90◦ for ◦ both stars at the time of one eclipse and ν = 270 at the other, thus leaving cos E0 = e, as given in the main text.

3 https://commons.wikimedia.org/wiki/File:Orbit1.svg B.2 newton’s method 97

Figure 66: True (ν) and eccentric (E) anomaly. C=centre, F=focal point, a=major axis, b=minor axis, e=eccentricity.4

B.2NEWTON’SMETHOD

Newton’s method (sometimes also called Newton-Raphson method, after Isaac New- ton and Joseph Raphson) is a numerical approach for ﬁnding the zeroes of a real function f (x). One starts with an initial guess xn and takes the tangent to the function at this point. The tangent’s equation is

0 y − f (xn) = f (xn)(x − xn) (17)

0 where f (xn) is the derivative of the function f at the point xn. The tangent’s zero is obtained by setting y = 0. As Figure 67 shows, this zero is a better approximation for the zero of the function f (x) than the initial guess. Calling the zero of the tangent xn+1, one has thus obtained an iterative formula for the computation of the function’s zero:

f (xn) xn+1 = xn − 0 (18) f (xn) The iteration may be stopped when there is no more difference between succeeding computed values or the difference falls below a pre-deﬁned value, depending on the desired accuracy. For the eccentricity calculations in this thesis, I set the limit at en+1 − −6 en = 10 . The method will usually converge if the initial guess is close enough to the function’s 0 zero and f (x0) 6= 0. In some cases, if the function has more than one zero, the method 4 Adapted from https://commons.wikimedia.org/wiki/File:Eccentric_and_True_Anomaly.svg. 98 APPENDIXB-CONCEPTSANDMETHODS

Figure 67: Illustration of Newton’s method.5

may always converge on the same zero, irrespective of the initial guess. Also, for some functions, an inﬁnite cycle may be entered, where the method oscillates between two values indeﬁnitely. In such cases, one must fall back on other numerical methods.

B.3CALCULATIONOFINTRINSICSTARCOLOURS

A star’s true or intrinsic colour is reddened due to absorption and scattering by in-

terstellar dust. The difference between intrinsic colour, for example (B − V)0, and observed colour (B − V) is the colour excess:

EB−V = (B − V) − (B − V)0 = (B − B0) − (V − V0) = AB − AV (19)

where AB and AV are the extinctions in the photometric B and V bands. For the visual extinction the following relation has been established:

AV ≈ 3.1 EB−V (20)

Furthermore, the following empiric relation between EU−B and EB−V has been found:

EU−B = (0.72 + 0.05 EB−V )EB−V (21)

5 http://www.codewithc.com/wp-content/uploads/2015/02/newton1.png B.3 calculation of intrinsic star colours 99

Inserting EU−B = (U − B) − (U − B)0 and EB−V = (B − V) − (B − V)0 into this equation and solving for (U − B) we ﬁnd

(U − B) = (U − B)0 − 0.72[(B − V)0 − (B − V)] 2 2 + 0.05[(B − V)0 + (B − V) ] − 0.1(B − V)(B − V)0 (22)

Obviously, since this equation contains two unknowns, (U − B)0 and (B − V)0, it cannot be solved as such. Using the intrinsic colours provided by Fitzgerald 1970, I adopted the following algorithmic approach to the problem: For any given (B − V),

I calculated (U − B) for all (U − B)0, (B − V)0 pairs in the range O5 to B9.5 and selected the pair which gave the (U − B) closest to the measured value as the intrinsic colour. I used only this range of intrinsic colours for the following reason. In Figure 68

Figure 68: Illustration of reddening. Squares=unreddened main sequence, dots=EB sample with UBV data, red lines=reddening paths. reddening is illustrated graphically in a slightly modiﬁed version of the colour-colour diagram shown in Chapter 4. Reddening paths calculated according to equation 21 are shown for three representative spectral types. These illustrate that my method might 100 APPENDIXB-CONCEPTSANDMETHODS

run into problems for spectral types later than B6, as for these, the reddening path intersects the main sequence in more than one place. For a strongly reddened late B star, a much later spectral type might thus be calculated. Looking again at Figure 68, however, it is clear that no star in the diagram can have a spectral type later than B9. For the few stars where a solution corresponding to a later spectral type would math- ematically be possible, the extinction vector would then point in the wrong direction. Thus, I deemed it admissible to circumvent the above mentioned problem by simply excluding later spectral type from the calculation right away. From Figure 68 it appears that a few stars might even be earlier than O5, the earliest type for which Fitzgerald provides intrinsic colours. It must be pointed out that there are still several other uncertainties inherent in the spectral type determination. First, the relation given in equation 21 is an average over the whole sky, second, strictly speaking, the parameters may change slightly with spectral type. Third, it is dependent on the luminosity class – I assumed all stars to be dwarfs, which will cover most of the sample, but will not be accurate in every single case. Taking all these facts into consideration, as well as the errors inherent in the UBV measurements, the spectral types given in this thesis should only be seen as estimates. BIBLIOGRAPHY

[Barr Domínguez 2014] Barr Domínguez, A.: Eclipsing high-mass binary stars, Ruhr- Universität Bochum, Diss., 2014

[Barr Domínguez et al. 2013] Barr Domínguez, A. ; Chini, R. ; Haas, M. ; Pozo Nuñez, F. ; Hackstein, M. ; Drass, H. ; Lemke, R. ; Murphy, M.: VizieR Online Data Catalog: 3 eclipsing high-mass binaries light curve (Barr Domínguez+, 2013). In: VizieR Online Data Catalog 355 (2013), August

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My sincere thanks go to:

My supervisor Rolf Chini for enabling me to write this thesis in the ﬁrst place, for his unfailing support and advice and the opportunity to spend time at the Univer- sitätssternwarte Bochum and the La Silla observatory.

My second supervisor Horst Fichtner for taking an interest in my work and for agree- ing to act as second reviewer whilst having lots of other theses on his desk.

My colleagues, several of whom have become dear friends in the course of the last three and a half years. In particular, I would like to thank Moritz, Michael, Christian, Martin and Francisco for sharing their expertise with me; Christofer for providing me with the results of his classiﬁer; Angie for our fruitful collaboration; Roland for teach- ing me remote observing with the La Silla 1 m telescope – and all of you for being such fun to be around and all the good times we shared along the way. Michael and Francisco I would additionally like to thank for always being there to help when I ran into problems at the observatory.

My parents and my grandmother Maria, for their unconditional love, support and en- couragement.

This document was typeset in LATEX using the typographical look-and-feel classicthesis developed by André Miede. The style was inspired by Robert Bringhurst’s seminal book on typography “The Elements of Typographic Style”.

105

CURRICULUMVITAE

Personal data

Name: Lena Maria Surname: Kaderhandt Date of birth: 18 May 1986 Place of birth: Herdecke, Germany Nationality: German

Education

April 2013 – December 2016 PhD student at the Astronomical Institute of the Ruhr-Universität Bochum Thesis: "B-type Eclipsing Binary Stars in the Bochum Galactic Disk Survey" (supervisor: Prof. Dr. Rolf Chini)

October 2008 – March 2012 Student of physics at the Friedrich-Schiller-Universität Jena Diploma thesis: "Circular Orbits of Neutral Test Particles in Modiﬁed Reissner- Nordström-de Sitter Spacetime" (supervisor: Prof. Dr. Gerhard Schäfer)

October 2005 – July 2008 Student of physics at the Ruhr-Universität Bochum

June 2005 Abitur at the Schiller-Gymnasium Witten

DECLARATION

Versicherung gemäß §7 Abs. 2 Nr. 6 PromO 2011

Ich versichere, dass ich meine Dissertation selbstständig angefertigt und ver- fasst und keine anderen als die angegebenen Hilfsmittel und Hilfen benutzt habe. Meine Dissertation habe ich in dieser oder ähnlicher Form noch bei keiner anderen Fakultät der Ruhr-Universität Bochum oder bei einer anderen Hochschule eingereicht.

I hereby certify that this dissertation has been composed by myself and is based on my own work, unless stated otherwise. My dissertation has not been sub- mitted for any other degree in any faculty of the Ruhr-Universität Bochum or any other tertiary institution.

Lena Maria Kaderhandt