DOCSLIB.ORG

Publications of the Astronomical Society of the Pacific

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Publications of the Astronomical Society of the Pacific PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC Vol. 80 August 1968 No. 475 PULSATING STARS DAVID S. KING Department of Physics and Astronomy University of New Mexico and JOHN P. COX Department of Physics and Astrophysics and Joint Institute for Laboratory Astrophysics University of Colorado Received March 13, 1968 The current status of our understanding of the causes and nature of stellar pulsation, as applied to classical cepheids, RR Lyrae variables, and W Virginis variables, is reviewed. The historical development of these ideas is briefly surveyed, with emphasis on the search for the excitation mechanism ( s ). Tests of the idea that the instability is due to the ionization of one or more of the elements H, He, and He+ in the stellar envelope, by means of both the linear and the more recent nonlinear calculations, are described and summarized. Some comparisons of theory and observation are made, particularly with respect to the period-luminosity relation, location of variables in the Hertzsprung-Russell diagram, fundamental versus first overtone mode, and phase relations between light and velocity curves. A number of special prob- lems are discussed, including causes of the limitation of the pulsation ampli- tude to the observed values, relations between the light and velocity variations, and the interaction between pulsations and convection. A new physical inter- pretation, due to J. Castor, of the well-known "phase lag discrepancy" be- tween the luminosity and radius variations is described. A number of pre- viously unpublished results are presented, particularly with respect to recent nonlinear stellar pulsation calculations. I. Introduction The RR Lyrae variables, classical cepheids, and W Virginis vari- ables constitute a very important class of stellar objects. The well- 365 © Astronomical Society of the Pacific · Provided by the NASA Astrophysics Data System 366 D. S. KING AND J. P. COX known period-luminosity relation of classical cepheids makes pos- sible the use of these stars as indicators of distance within our own galaxy as well as for nearby extragalactic systems. Recent theoretical work also points to the possibility of a better understanding of the interiors of giant and supergiant stars through a study of their pulsation characteristics. The question of the physical nature of such pulsations is therefore of great interest to a very large seg- ment of astronomy. The discussion which follows will pertain pri- marily to the types of variable stars just mentioned, although much of the theory appears to be equally valid for such stars as the δ Scuti variables, RV Tauri variables, and the dwarf cepheids. No attempt will be made here to give a detailed survey of the extensive observational material which is available for such stars. However, for orientation we list in Table I some of the more basic data for the RR Lyrae variables, the classical cepheids, and the W Virginis variables. The ranges in median absolute magnitude given in this table are approximate and include some allowance for observational uncertainties. In Table II we list some properties of classical cepheids. In this table the mean luminosities (L) and effective temperatures ( Te ) have been computed from the period- luminosity and period-color relations given by Kraft ( 1963 ). The masses (¾)^) are estimates based on the evolutionary tracks com- puted without mass loss by Hofmeister, Kippenhahn, and Weigert (1964a,b,c); Kippenhahn, Thomas, and Weigert (1965); and Hof- meister (1967a). The Q values are computed from the listed values of and R. Further observational facts will be introduced where appropriate during the discussion of various theoretical problems. Excellent and detailed summaries of the basic observa- tional material have been provided by, e.g., Payne-Gaposchkin and Gaposchkin (1963), Payne-Gaposchkin (1954), Ledoux and Wal- TABLE I Pulsating Variables Range of Median Kind of Range of Characteristic Population Median Absolute Star Periods Period Type Spectral Type Magnitude RR Lyrae IbS to 24h 0^5 II A2 to F6 -f 0.5 to -fl Classical Cepheids 1* to 50d 5d to 1(^ I F6 to K2 -0.5 to-6 W Virginis 2d to 45d 12d to 20d II F2 to G6( ?) 0.0 to-3 © Astronomical Society of the Pacific · Provided by the NASA Astrophysics Data System PULSATING STARS 367 TABLE II Properties of Classical Cepheids From To 1« 50d 380L,Ό 31?000Lo F5 G5 6900oK 5400oK 14¾ 200Rq 3.7%Í ivt© imQ 0^037 0-066 raven (1958), and Kukarkin and Parenago (1963); these may be consulted for further details. Two very recent observational dis- cussions of the period-luminosity relation of classical cepheids are by Sandage and Tammann (1968) and by Femie (1967). The theoretical study of pulsating variable stars has been con- siderably advanced in the past ten years. This progress can be attributed in large part to the availability of modem electronic computers which have made it possible to treat the equations appropriate to radial pulsations in their fully nonlinear form. One of the main purposes of this paper is to review some of the more important aspects of this work. Other recent reviews of stellar pulsation theory are provided by Ledoux and Walraven (1958); Ledoux and Whitney ( 1961 ) ; Ledoux ( 1963, 1965 ) ; Zhevakin (1963); Christy (1966b, 1967d); Cox (1967); and Cox and Cox (1967). Earlier reviews have been provided by Eddington (1926), Chapter 8; and Rosseland ( 1949 ). See also the proceedings of the 1965 I.A.U. Bamberg Symposium, The Position of Variable Stars in the Hertzsprung-Russell Diagram. One can characterize the state of our present knowledge by point- ing to the steps which led to it: (a) the establishment of the nature of the light and radial velocity variations and the search for the mechanism ( or mechanisms ) responsible for the maintenance of the pulsations; (b) studies involving the linearized pulsation equations which tended to confirm the effectiveness of "envelope ionization mechanisms" (in particular, the second helium, first helium, and hydrogen ionization zones) in exciting pulsations; (c) solutions of the fully nonlinear pulsation equations; further confirmation of the effectiveness of these envelope ionization mechanisms as sources © Astronomical Society of the Pacific · Provided by the NASA Astrophysics Data System 368 D. S. KING AND J. P. COX of excitation (or "driving") for pulsations in the envelopes of stars; (d) the study of a number of interesting problems, both linear and nonlinear, such as the growth rate of the pulsation amplitude, the approach to limiting amplitude, the phase relations between the light and velocity variations, and the interaction between pul- sations and convection. The plan of this paper will follow the above list of topics. II. Establishment of the Nature of the Variations and the Search for the Excitation Mechanism The concept of radial pulsations of stellar masses as the explana- tion of the observed cepheid phenomena was first given a firm mathematical foundation by Eddington (1926). He assumed that the oscillations were very small and essentially adiabatic, and de- rived and studied solutions of the adiabatic wave equation for such oscillations. Perhaps the most important and far-reaching result of these studies was the theoretical derivation of the well- known "period-mean density" relation which is apparently obeyed by actual pulsating stars: Π(ί5/ρο)4 = Ç , (1) where Π is the period; ρ and /3© are the mean densities of, respec- tively, the star and the sun; and Ç is the "pulsation constant," a slowly varying function of the properties and internal structure (particularly the central mass concentration) of the stellar model. For the fundamental mode of the homogeneous (uniform density) model the value of Q is Ç = 27r/[(3r1 —4) (4/3)^]^ , (2) where G is the constant of gravitation and T1 is one of the adiabatic exponents ( assumed constant throughout the star in equation (2)): ζ dlnP ν ζ 0 ν · (3) where Ρ and ρ are total pressure and density, respectively. The value of Q given by (2) is the largest possible value for a star of given Γι whose density does not increase outward, and is 0^116 for Γι == 5/3. For more realistic distributions of density the theoretical values of Q generally lie in the range (K03-CW6 for Tt = 5/3. The © Astronomical Society of the Pacific · Provided by the NASA Astrophysics Data System PULSATING STARS 369 theoretical values of Q are insensitive to effects of nonadiabaticity and nonlinearity ( Q is increased on the order of a few percent for extremely large pulsation amplitudes where the radial excursion is comparable to the radius itself). Empirical values of Q are some- what uncertain, but generally appear to lie in the range 0^03-0^08, in good agreement with theoretical values. Physically, equation (1) may be interpreted roughly as a statement that the pulsation period is of the order of the time required for a sound wave to travel through the diameter of the star. Hence, small, compact stars have shorter periods than do large, tenuous stars. Eddington also studied the problem of the maintenance of the pulsations and the related problem of the dissipation of pulsation energy. He obtained an expression for the total dissipation of pulsational energy in a star which was subjected to a small radial perturbation. This dissipation is given for a star which in its un- perturbed state is in both hydrostatic and thermal equilibrium by; (δΤ/Τ) dp (4) vol where the volume is that of the entire star and the cyclic integral extends over one pulsation period of the star, δ Τ is the instan- taneous temperature excess of a volume element over its average or equilibrium value and dÇ is the instantaneous gain of heat per unit volume. Eddington used this equation to calculate the time of decay for the pulsations of a model which was supposed to repre- sent δ Cephei, the prototype for variable stars of the classical cepheid variety.
Load more

Recommended publications
  • Standing on the Shoulders of Giants: New Mass and Distance Estimates
    Draft version October 15, 2020 Typeset using LATEX twocolumn style in AASTeX63 Standing on the shoulders of giants: New mass and distance estimates for Betelgeuse through combined evolutionary, asteroseismic, and hydrodynamical simulations with MESA Meridith Joyce,1, 2 Shing-Chi Leung,3 Laszl´ o´ Molnar,´ 4, 5, 6 Michael Ireland,1 Chiaki Kobayashi,7, 8, 2 and Ken'ichi Nomoto8 1Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia 2ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australia 3TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, Caltech, Pasadena, CA 91125, USA 4Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Konkoly-Thege ´ut15-17, H-1121 Budapest, Hungary 5MTA CSFK Lendulet¨ Near-Field Cosmology Research Group, Konkoly-Thege ´ut15-17, H-1121 Budapest, Hungary 6ELTE E¨otv¨os Lor´and University, Institute of Physics, Budapest, 1117, P´azm´any P´eter s´et´any 1/A 7Centre for Astrophysics Research, Department of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK 8Kavli Institute for the Physics and Mathematics of the Universe (WPI),The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan (Dated: Accepted XXX. Received YYY; in original form ZZZ) ABSTRACT We conduct a rigorous examination of the nearby red supergiant Betelgeuse by drawing on the synthesis of new observational data and three different modeling techniques. Our observational results include the release of new, processed photometric measurements collected with the space-based SMEI instrument prior to Betelgeuse's recent, unprecedented dimming event.
    [Show full text]
  • Plotting Variable Stars on the H-R Diagram Activity
    Pulsating Variable Stars and the Hertzsprung-Russell Diagram The Hertzsprung-Russell (H-R) Diagram: The H-R diagram is an important astronomical tool for understanding how stars evolve over time. Stellar evolution can not be studied by observing individual stars as most changes occur over millions and billions of years. Astrophysicists observe numerous stars at various stages in their evolutionary history to determine their changing properties and probable evolutionary tracks across the H-R diagram. The H-R diagram is a scatter graph of stars. When the absolute magnitude (MV) – intrinsic brightness – of stars is plotted against their surface temperature (stellar classification) the stars are not randomly distributed on the graph but are mostly restricted to a few well-defined regions. The stars within the same regions share a common set of characteristics. As the physical characteristics of a star change over its evolutionary history, its position on the H-R diagram The H-R Diagram changes also – so the H-R diagram can also be thought of as a graphical plot of stellar evolution. From the location of a star on the diagram, its luminosity, spectral type, color, temperature, mass, age, chemical composition and evolutionary history are known. Most stars are classified by surface temperature (spectral type) from hottest to coolest as follows: O B A F G K M. These categories are further subdivided into subclasses from hottest (0) to coolest (9). The hottest B stars are B0 and the coolest are B9, followed by spectral type A0. Each major spectral classification is characterized by its own unique spectra.
    [Show full text]
  • The Interaction of Accretion Flux with Stellar Pulsation J.C
    340 THE INTERACTION OF ACCRETION FLUX WITH STELLAR PULSATION J.C. Papaloizou J.E. Pringle The Institute of Astronomy, Cambridge, UK We consider the usual hypothesis that the short period coherent oscillations seen in cataclysmic variables are attributable to g-modes in a slowly rotating star, for details see Papaloizou and Pringle (1977). We show that this hypothesis is untenable for three main reasons: (i) the observed periods are too short for reasonable white dwarf models, (ii) the observed variability of the oscillations is too rapid and (iii) the expected rotation of the white dwarf, due to accretion, invalidates the slow rotation as­ sumption on which standard g-mode theory is based. We investigate the low frequency spectrum of a rotating pulsating star, taking the effects of rotation fully into account. In this case there are two sets of low frequency modes, the g-modes, and modes similar to Rossby waves in the Earth's atmosphere and oceans, which we designate r-modes. Typical periods for such modes are 1/m times the rotation period of the white dwarfs outer layers (m is the azimuthal wave number). We conclude that non-radial oscillations of white dwarfs can account for the properties of the oscillations seen in dwarf novae. References Papaloizou, J.C. and Pringle, J.E., 1977, Mon. Not R. Astr. Soc, in press. DISCUSSION of paper by PAPALOIZOU and PRINGLE: KIPPENHAHN: Since the vibrational stability of white dwarfs has been mentioned several times now, I would like to report on some unpublished results obtained by Lauterborn about 10 years ago.
    [Show full text]
  • Pre-Supernova Evolution of Massive Stars
    Pre-Supernova Evolution of Massive Stars ByNINO PANAGIA1;2, AND GIUSEPPE BONO3 1Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA. 2On assignment from the Space Science Department of ESA. 3Osservatorio Astronomico di Roma, Via Frascati 33, Monte Porzio Catone, Italy. We present the preliminary results of a detailed theoretical investigation on the hydrodynamical properties of Red Supergiant (RSG) stars at solar chemical composition and for stellar masses ranging from 10 to 20 M . We find that the main parameter governing their hydrodynamical behaviour is the effective temperature, and indeed when moving from higher to lower effective temperatures the models show an increase in the dynamical perturbations. Also, we find that RSGs are pulsationally unstable for a substantial portion of their lifetimes. These dynamical instabilities play a key role in driving mass loss, thus inducing high mass loss rates (up to −3 −1 almost 10 M yr ) and considerable variations of the mass loss activity over timescales of the order of 104 years. Our results are able to account for the variable mmass loss rates as implied by radio observations of type II supernovae, and we anticipate that comparisons of model predictions with observed circumstellar phenomena around SNII will provide valuable diagnostics about their progenitors and their evolutionary histories. 1. Introduction More than 20 years of radio observations of supernovae (SNe) have provided a wealth of evidence for the presence of substantial amounts of circumstellar material (CSM) surrounding the progenitors of SNe of type II and Ib/c (see Weiler et al., this Conference, and references therein).
    [Show full text]
  • Variable Star Classification and Light Curves Manual
    Variable Star Classification and Light Curves An AAVSO course for the Carolyn Hurless Online Institute for Continuing Education in Astronomy (CHOICE) This is copyrighted material meant only for official enrollees in this online course. Do not share this document with others. Please do not quote from it without prior permission from the AAVSO. Table of Contents Course Description and Requirements for Completion Chapter One- 1. Introduction . What are variable stars? . The first known variable stars 2. Variable Star Names . Constellation names . Greek letters (Bayer letters) . GCVS naming scheme . Other naming conventions . Naming variable star types 3. The Main Types of variability Extrinsic . Eclipsing . Rotating . Microlensing Intrinsic . Pulsating . Eruptive . Cataclysmic . X-Ray 4. The Variability Tree Chapter Two- 1. Rotating Variables . The Sun . BY Dra stars . RS CVn stars . Rotating ellipsoidal variables 2. Eclipsing Variables . EA . EB . EW . EP . Roche Lobes 1 Chapter Three- 1. Pulsating Variables . Classical Cepheids . Type II Cepheids . RV Tau stars . Delta Sct stars . RR Lyr stars . Miras . Semi-regular stars 2. Eruptive Variables . Young Stellar Objects . T Tau stars . FUOrs . EXOrs . UXOrs . UV Cet stars . Gamma Cas stars . S Dor stars . R CrB stars Chapter Four- 1. Cataclysmic Variables . Dwarf Novae . Novae . Recurrent Novae . Magnetic CVs . Symbiotic Variables . Supernovae 2. Other Variables . Gamma-Ray Bursters . Active Galactic Nuclei 2 Course Description and Requirements for Completion This course is an overview of the types of variable stars most commonly observed by AAVSO observers. We discuss the physical processes behind what makes each type variable and how this is demonstrated in their light curves. Variable star names and nomenclature are placed in a historical context to aid in understanding today’s classification scheme.
    [Show full text]
  • Determining Pulsation Period for an RR Lyrae Star
    Leah Fabrizio Dr. Mitchell 06/10/2010 Determining Pulsation Period for an RR Lyrae Star As children we used to sing in wonderment of the twinkling stars above and many of us asked, “Why do stars twinkle?” All stars twinkle because their emitted light travels through the Earth’s atmosphere of turbulent gas and clouds that move and shift causing the traversing light to fluctuate. This means that the actual light output of the star is not changing. However there are a number of stars called Variable Stars that actually produce light of varying brightness before it hits the Earth’s atmosphere. There are two categories of variable stars: the intrinsic, where light fluctuation is due from the star physically changing and producing different luminosities, and extrinsic, where the amount of starlight varies due to another star eclipsing or blocking the star’s light from reaching earth (AAVSO 2010). Within the category of intrinsic variable stars are the pulsating variables that have a periodic change in brightness due to the actual size and light production of the star changing; within this group are the RR Lyrae stars (“variable star” 2010). For my research project, I will observe an RR Lyrae and find the period of its luminosity pulsation. The first RR Lyrae star was named after its namesake star (Strobel 2004). It was first found while astronomers were studying the longer period variable stars Cepheids and stood out because of its short period. In comparison to Cepheids, RR Lyraes are smaller and therefore fainter with a shorter period as well as being much older.
    [Show full text]
  • A Refined Search for Pulsations in White Dwarf Companions To
    MNRAS 479, 1267–1272 (2018) doi:10.1093/mnras/sty1546 Advance Access publication 2018 June 12 A refined search for pulsations in white dwarf companions to millisecond pulsars Mukremin Kilic,1,2† J. J. Hermes,3‡ A. H. Corsico,´ 4 Alekzander Kosakowski,1 Warren R. Brown,5 John Antoniadis,6 Leila M. Calcaferro,4 A. Gianninas,1 Leandro G. Althaus4 and M. J. Green7 1Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019, USA 2Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK 3Department of Physics and Astronomy, University of North Carolina, Chapel Hill NC 27599, USA 4Facultad de Ciencias Astronomicas´ y Geof´ısicas (UNLP), La Plata, Argentina 5Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge MA 02138, USA 6Dunlap Institute for Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto M5S 3H4, Canada 7Astronomy and Astrophysics Group, Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK Accepted 2018 June 7. Received 2018 May 27; in original form 2018 April 11 ABSTRACT We present optical high-speed photometry of three millisecond pulsars with low-mass (<0.3 M) white dwarf companions, bringing the total number of such systems with follow-up time-series photometry to five. We confirm the detection of pulsations in one system, the white dwarf companion to PSR J1738+0333, and show that the pulsation frequencies and amplitudes are variable over many months. A full asteroseismic analysis for this star is underconstrained, but the mode periods we observe are consistent with expectations for an M = 0.16 − 0.19 M white dwarf, as suggested from spectroscopy.
    [Show full text]
  • Nd AAS Meeting Abstracts
    nd AAS Meeting Abstracts 101 – Kavli Foundation Lectureship: The Outreach Kepler Mission: Exoplanets and Astrophysics Search for Habitable Worlds 200 – SPD Harvey Prize Lecture: Modeling 301 – Bridging Laboratory and Astrophysics: 102 – Bridging Laboratory and Astrophysics: Solar Eruptions: Where Do We Stand? Planetary Atoms 201 – Astronomy Education & Public 302 – Extrasolar Planets & Tools 103 – Cosmology and Associated Topics Outreach 303 – Outer Limits of the Milky Way III: 104 – University of Arizona Astronomy Club 202 – Bridging Laboratory and Astrophysics: Mapping Galactic Structure in Stars and Dust 105 – WIYN Observatory - Building on the Dust and Ices 304 – Stars, Cool Dwarfs, and Brown Dwarfs Past, Looking to the Future: Groundbreaking 203 – Outer Limits of the Milky Way I: 305 – Recent Advances in Our Understanding Science and Education Overview and Theories of Galactic Structure of Star Formation 106 – SPD Hale Prize Lecture: Twisting and 204 – WIYN Observatory - Building on the 308 – Bridging Laboratory and Astrophysics: Writhing with George Ellery Hale Past, Looking to the Future: Partnerships Nuclear 108 – Astronomy Education: Where Are We 205 – The Atacama Large 309 – Galaxies and AGN II Now and Where Are We Going? Millimeter/submillimeter Array: A New 310 – Young Stellar Objects, Star Formation 109 – Bridging Laboratory and Astrophysics: Window on the Universe and Star Clusters Molecules 208 – Galaxies and AGN I 311 – Curiosity on Mars: The Latest Results 110 – Interstellar Medium, Dust, Etc. 209 – Supernovae and Neutron
    [Show full text]
  • Searching for RR Lyrae Stars in M15
    Searching for RR Lyrae Stars in M15 ARCC Scholar thesis in partial fulfillment of the requirements of the ARCC Scholar program Khalid Kayal February 1, 2013 Abstract The expansion and contraction of an RR Lyrae star provides a high level of interest to research in astronomy because of the several intrinsic properties that can be studied. We did a systematic search for RR Lyrae stars in the globular cluster M15 using the Catalina Real-time Transient Survey (CRTS). The CRTS searches for rapidly moving Near Earth Objects and stationary optical transients. We created an algorithm to create a hexagonal tiling grid to search the area around a given sky coordinate. We recover light curve plots that are produced by the CRTS and, using the Lafler-Kinman search algorithm, we determine the period, which allows us to identify RR Lyrae stars. We report the results of this search. i Glossary of Abbreviations and Symbols CRTS Catalina Real-time Transient Survey RR A type of variable star M15 Messier 15 RA Right Ascension DEC Declination RF Radio frequency GC Globular cluster H-R Hertzsprung-Russell SDSS Sloan Digital Sky Survey CCD Couple-Charged Device Photcat DB Photometry Catalog Database FAP False Alarm Probability ii Contents 1 Introduction 1 2 Background on RR Lyrae Stars 5 2.1 What are RR Lyraes? . 5 2.2 Types of RR Lyrae Stars . 6 2.3 Stellar Evolution . 8 2.4 Pulsating Mechanism . 9 3 Useful Tools and Surveys 10 3.1 Choosing M15 . 10 3.2 Catalina Real-time Transient Survey . 11 3.3 The Sloan Digital Sky Survey .
    [Show full text]
  • Gaia Data Release 2 Special Issue
    A&A 623, A110 (2019) Astronomy https://doi.org/10.1051/0004-6361/201833304 & © ESO 2019 Astrophysics Gaia Data Release 2 Special issue Gaia Data Release 2 Variable stars in the colour-absolute magnitude diagram?,?? Gaia Collaboration, L. Eyer1, L. Rimoldini2, M. Audard1, R. I. Anderson3,1, K. Nienartowicz2, F. Glass1, O. Marchal4, M. Grenon1, N. Mowlavi1, B. Holl1, G. Clementini5, C. Aerts6,7, T. Mazeh8, D. W. Evans9, L. Szabados10, A. G. A. Brown11, A. Vallenari12, T. Prusti13, J. H. J. de Bruijne13, C. Babusiaux4,14, C. A. L. Bailer-Jones15, M. Biermann16, F. Jansen17, C. Jordi18, S. A. Klioner19, U. Lammers20, L. Lindegren21, X. Luri18, F. Mignard22, C. Panem23, D. Pourbaix24,25, S. Randich26, P. Sartoretti4, H. I. Siddiqui27, C. Soubiran28, F. van Leeuwen9, N. A. Walton9, F. Arenou4, U. Bastian16, M. Cropper29, R. Drimmel30, D. Katz4, M. G. Lattanzi30, J. Bakker20, C. Cacciari5, J. Castañeda18, L. Chaoul23, N. Cheek31, F. De Angeli9, C. Fabricius18, R. Guerra20, E. Masana18, R. Messineo32, P. Panuzzo4, J. Portell18, M. Riello9, G. M. Seabroke29, P. Tanga22, F. Thévenin22, G. Gracia-Abril33,16, G. Comoretto27, M. Garcia-Reinaldos20, D. Teyssier27, M. Altmann16,34, R. Andrae15, I. Bellas-Velidis35, K. Benson29, J. Berthier36, R. Blomme37, P. Burgess9, G. Busso9, B. Carry22,36, A. Cellino30, M. Clotet18, O. Creevey22, M. Davidson38, J. De Ridder6, L. Delchambre39, A. Dell’Oro26, C. Ducourant28, J. Fernández-Hernández40, M. Fouesneau15, Y. Frémat37, L. Galluccio22, M. García-Torres41, J. González-Núñez31,42, J. J. González-Vidal18, E. Gosset39,25, L. P. Guy2,43, J.-L. Halbwachs44, N. C. Hambly38, D.
    [Show full text]
  • Many New Variable Stars Discovered in the Core of the Globular Cluster NGC 6715 (M 54) with EMCCD Observations DOI: 10.1051/0004-6361/201628864
    The University of Manchester Research Many new variable stars discovered in the core of the globular cluster NGC 6715 (M 54) with EMCCD observations DOI: 10.1051/0004-6361/201628864 Document Version Accepted author manuscript Link to publication record in Manchester Research Explorer Citation for published version (APA): Figuera Jaimes, R., Bramich, D. M., Kains, N., Skottfelt, J., Jørgensen, U. G., Horne, K., Dominik, M., Alsubai, K. A., Bozza, V., Burgdorf, M. J., Calchi Novati, S., Ciceri, S., D'Ago, G., Evans, D. F., Galianni, P., Gu, S. H., W Harpsøe, K. B., Haugbølle, T., Hinse, T. C., ... Wertz, O. (2016). Many new variable stars discovered in the core of the globular cluster NGC 6715 (M 54) with EMCCD observations. Astronomy and Astrophysics, 592, [A120]. https://doi.org/10.1051/0004-6361/201628864 Published in: Astronomy and Astrophysics Citing this paper Please note that where the full-text provided on Manchester Research Explorer is the Author Accepted Manuscript or Proof version this may differ from the final Published version. If citing, it is advised that you check and use the publisher's definitive version. General rights Copyright and moral rights for the publications made accessible in the Research Explorer are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Takedown policy If you believe that this document breaches copyright please refer to the University of Manchester’s Takedown Procedures [http://man.ac.uk/04Y6Bo] or contact [email protected] providing relevant details, so we can investigate your claim.
    [Show full text]
  • Stars and Their Spectra: an Introduction to the Spectral Sequence Second Edition James B
    Cambridge University Press 978-0-521-89954-3 - Stars and Their Spectra: An Introduction to the Spectral Sequence Second Edition James B. Kaler Index More information Star index Stars are arranged by the Latin genitive of their constellation of residence, with other star names interspersed alphabetically. Within a constellation, Bayer Greek letters are given first, followed by Roman letters, Flamsteed numbers, variable stars arranged in traditional order (see Section 1.11), and then other names that take on genitive form. Stellar spectra are indicated by an asterisk. The best-known proper names have priority over their Greek-letter names. Spectra of the Sun and of nebulae are included as well. Abell 21 nucleus, see a Aurigae, see Capella Abell 78 nucleus, 327* ε Aurigae, 178, 186 Achernar, 9, 243, 264, 274 z Aurigae, 177, 186 Acrux, see Alpha Crucis Z Aurigae, 186, 269* Adhara, see Epsilon Canis Majoris AB Aurigae, 255 Albireo, 26 Alcor, 26, 177, 241, 243, 272* Barnard’s Star, 129–130, 131 Aldebaran, 9, 27, 80*, 163, 165 Betelgeuse, 2, 9, 16, 18, 20, 73, 74*, 79, Algol, 20, 26, 176–177, 271*, 333, 366 80*, 88, 104–105, 106*, 110*, 113, Altair, 9, 236, 241, 250 115, 118, 122, 187, 216, 264 a Andromedae, 273, 273* image of, 114 b Andromedae, 164 BDþ284211, 285* g Andromedae, 26 Bl 253* u Andromedae A, 218* a Boo¨tis, see Arcturus u Andromedae B, 109* g Boo¨tis, 243 Z Andromedae, 337 Z Boo¨tis, 185 Antares, 10, 73, 104–105, 113, 115, 118, l Boo¨tis, 254, 280, 314 122, 174* s Boo¨tis, 218* 53 Aquarii A, 195 53 Aquarii B, 195 T Camelopardalis,
    [Show full text]