DOCSLIB.ORG

Preliminary Analysis of ULPC Light Curves Using Fourier

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Preliminary Analysis of ULPC Light Curves Using Fourier Preliminary Analysis of ULPC Light Curves Using Fourier Decomposition Technique Chow-Choong Ngeow‡, Scott Lucchini∗, Shashi Kanbur†, Brittany Barrett† and Bin Lin∗ ‡Graduate Institute of Astronomy, National Central University, Jhongli 32001, Taiwan ∗Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627, USA †Department of Physics, SUNY Oswego, Oswego, NY 13126, USA Abstract—Recent work on Ultra Long Period Cepheids For the six stars in the LMC and the SMC, we obtained the (ULPCs) has suggested their usefulness as a distance indicator, V-band data from [1] and the I-band data from [2]. We also but has not commented on their relationship as compared with acquired additional V- and I-band data through the McMaster other types of variable stars. In this work, we use Fourier analysis 1 to quantify the structure of ULPC light curves and compare Cepheid Photometry Archive for four ULPCs in the LMC. them to Classical Cepheids and Mira variables. Our preliminary [3] had some additional data points for HV 883 and HV 2447. results suggest that the low order Fourier parameters (Rk1 and Also, for HV 2883 and HV 5497, we acquired data from [4], φk1) of ULPCs show a continuous trend defined by Classical again through the McMaster Archive. [1] also had V- and I- Cepheids after the resonance around 10 days. However their band data for the five stars in NGC 55, the three stars in NGC Fourier parameters also overlapped with those from Miras, which make the classification of long period variable stars difficult based 300, and the one star in NGC 6822. Again, using the McMaster on the light curves information alone. Archive, additional photometry was acquired for NGC 300-1 Keywords — Cepheids; late-type stars; distance scale (as named by [1]) from [3]. The photometric V- and I-band data for the two stars in I Zw 18 were obtained from [5]. I. INTRODUCTION The periods for these stars were also compiled in [1]. In Cepheid variables are key component in astrophysical re- Table I we have listed all the ULPCs in our data set together search, as they are an indispensable link in the extragalactic with their periods and host galaxies. In this Table, the names distance ladder. However, for the most part, current research of the stars (Column 1) are consistent with those used by focuses on Classical Cepheids with periods less than 60 days. [1]. Column 3 contains the distance modulus (DM) values for There are good reasons for this: in terms of sufficient phase the stars’ host galaxies listed in Column 2. The magnitudes coverage, they take less time to observe, and they have a well (Column 5) are the absolute, reddening corrected, mean V- defined period-luminosity (PL) relation. Also, Cepheids with band magnitudes as calculated by our Fourier analysis with periods greater than 100 days obey a different relation ([1]), orders as shown in Column 6. All the data for these stars was which has not been nearly as well documented. In this work, obtained from [1] and references therein, however for the stars we follow the same conventions as [1], defining these “Ultra where more data was compiled, footnotes have been added. Long Period Cepheids” (ULPCs) to be any fundamental mode Figure 1 presents the ULPC light curves used in this work. Cepheids with a pulsation period greater than 80 days. Even though ULPCs have generally not been studied as in- B. OGLE-III Catalog tensely as shorter period Cepheids, there are many advantages The third installment of the Optical Gravitational Lensing to acquiring data on these ULPCs. As the PL relation indicates, Experiment (OGLE-III) contains photometric data for many the longer the period of a star, the brighter it is. This means that variable stars in the Large and Small Magellanic Clouds. We arXiv:1309.4297v1 [astro-ph.SR] 17 Sep 2013 these variables can be observed at much greater distances than were interested in the V- and I-band photometric light curves are currently possible. This added brightness would allow us to data for fundamental mode Cepheids and longer period Mira- use Cepheids to measure distances out to 100 Mpc and beyond like variables. We also obtained the periods for all the stars [1]. In this work, our goal is to study the structural properties we used from the catalog. From OGLE-III LMC Cepheid of ULPC light curves. We are interested in comparing the light catalog ([6]), we chose 1,804 (out of 1,849) Cepheids based curves of ULPCs to shorter period Classical Cepheids as well on what data was available for these stars. We then obtained as to longer period Mira-like variables (Miras). the V- and I-band photometric light curve data for these II. DATA Cepheids. Similarly, of the 2,626 available fundamental mode Cepheids in the SMC ([7]), we selected 2,596. The OGLE-III A. ULPCs catalog also contains photometric and period data for ”long There is very limited data for ULPCs available right now, period variables” (LPVs). These LPVs are classified into three but we were able to compile data for 17 ULPCs in 6 different different types: Miras, OSARGs, and SRVs ([8]). We chose galaxies, including the Large and Small Magellanic Clouds (LMC/SMC), NGC 6822, NGC 55, NGC 300, and I Zw 18. 1http://crocus.physics.mcmaster.ca/Cepheid/ HV 883 HV 2447 HV 2883 HV 5497 -8 -8 -7.6 -8 -7.6 -7.2 -7.6 -7.6 -7.2 -6.8 -7.2 -6.8 -6.4 -7.2 -6.8 -6.4 -6 -6.8 -6.4 -6 -5.6 -6.4 -5.6 -6 -5.2 -5.2 -5.6 -4.8 -6 0 0.5 1 1.5 2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 HV 821 HV 829 NGC 6822 - 1 NGC 55 - 1 -8.4 -8.4 -7.2 -8.4 -8 -8 -6.8 -8 -6.4 -7.6 -7.6 -6 -7.6 -7.2 -7.2 -5.6 -7.2 -6.8 -6.8 -5.2 -6.4 -6.4 -4.8 -6.8 0 0.5 1 1.5 2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 NGC 55 - 2 NGC 55 - 3 NGC 55 - 4 NGC 55 - 5 -8 -7.6 -7.6 -7.2 -7.2 -7.2 -6.8 -7.6 -6.8 -6.8 -6.4 -7.2 -6.4 -6.4 -6 -6 -6.8 -6 -5.6 -5.6 -6.4 -5.6 -5.2 -5.2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 NGC 300 - 1 NGC 300 - 2 NGC 300 - 3 V1 V15 -7.6 -8.4 -8 -8.8 -9.2 -7.2 -8 -8.4 -8.8 -6.8 -7.6 -7.6 -8 -8.4 -6.4 -7.2 -7.6 -8 -6 -6.8 -7.2 -5.6 -6.4 -7.2 -7.6 -5.2 -6 -6.8 -6.8 -7.2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 0 0.5 1 1.5 2 Fig. 1. ULPC light curves with their respective Fourier fits. The absolute V (open squares) and I (filled squares) magnitudes are represented along the y-axis, and the phase of pulsation is along the x-axis. 1,407 of the listed 1,663 Mira variables and again used both their V- and I-band photometric data. TABLE I DATA ON THE ULPCS THAT WE USED. C. NGC 300 Cepheid Data Name Galaxy DM Period [days] MV N [9] acquired V- and I-band photometric data for 64 Cepheids HV 883a LMC 133.6 -6.30 4 from NGC 300 with periods ranging from 11 to 115 days. HV 2447a LMC 118.7 -6.47 4 However, three of the Cepheids have periods greater than 80 b 18.50 HV 2883 LMC 109.2 -5.98 3 days, so they are included as ULPCs, not as regular Cepheids HV 5497b LMC 98.6 -6.62 4 HV 821 SMC 127.5 -6.99 4 of NGC 300. The remaining 61 stars and their light curve data 18.93 HV 829 SMC 84.4 -7.00 4 were added to our Classical Cepheid data set. NGC 6822 - 1 NGC 6822 23.31 123.9 -5.41 3 NGC55-1 NGC55 175.9 -7.17 4 III. FOURIER ANALYSIS NGC 55 - 2 NGC 55 152.1 -6.87 3 NGC 55 - 3 NGC 5526.43 112.7 -6.21 3 We characterized the structure of all the observed light NGC 55 - 4 NGC 55 97.7 -5.89 4 curves in our data set using the technique of Fourier decompo- NGC 55 - 5 NGC 55 85.1 -5.58 3 NGC 300 - 1a NGC 300 115.8 -6.15 3 sition. That is, the following function was fit to the observed NGC 300 - 2 NGC 30026.37 89.1 -6.66 3 data for a given star: NGC 300 - 3 NGC 300 83.0 -7.11 2 V1 IZw18 129.8 -7.30 2 N 31.30 V15 I Zw 18 125.0 -7.62 2 mag(t)= A0 + X Ak sin(kωt + φk) (1) k=1 a Additional data from [3].
Load more

Recommended publications
  • Hierarchical Star Formation in Nearby Galaxies? M
    Astronomy & Astrophysics manuscript no. Rodriguez_2020_corr ©ESO 2020 October 28, 2020 Hierarchical star formation in nearby galaxies? M. J. Rodríguez1??, G. Baume1; 2 and C. Feinstein1; 2 1 Instituto de Astrofísica de La Plata (CONICET-UNLP), Paseo del bosque S/N, La Plata (B1900FWA), Argentina, 2 Facultad de Ciencias Astronómicas y Geofísicas - Universidad Nacional de La Plata, Paseo del bosque S/N, La Plata (B1900FWA), Argentina Accepted XXX. Received YYY; in original form ZZZ ABSTRACT Aims. The purpose of this work is to study the properties of the spatial distribution of the young population in three nearby galaxies in order to better understand the first stages of star formation. Methods. We used ACS/HST photometry and the "path-linkage criterion" in order to obtain a catalog of young stellar groups (YSGs) in the galaxy NGC 2403. We studied the internal distribution of stars in these YSGs using the Q parameter. We extended these analyses to the YSGs detected in in NGC 300 and NGC 253 our previous works. We built the young stars’ density maps for these three galaxies. Through these maps, we were able to identify and study young stellar structures on larger scales. Results. We found 573 YSGs in the galaxy NGC 2403, for which we derived their individual sizes, densities, luminosity function, and other fundamental characteristics. We find that the vast majority of the YSGs in NGC 2403, NGC 300 and NGC 253 present inner clumpings, following the same hierarchical behavior that we observed in the young stellar structures on larger scales in these galaxies. We derived values of the fractal dimension for these structures between ∼ 1.5 and 1.6.
    [Show full text]
  • ASTRONOMY and ASTROPHYSICS the Elliptical Galaxy Formerly Known As the Local Group: Merging the Globular Cluster Systems
    Astron. Astrophys. 358, 471–480 (2000) ASTRONOMY AND ASTROPHYSICS The elliptical galaxy formerly known as the Local Group: merging the globular cluster systems Duncan A. Forbes1,2, Karen L. Masters1, Dante Minniti3, and Pauline Barmby4 1 University of Birmingham, School of Physics and Astronomy, Edgbaston, Birmingham B15 2TT, UK 2 Swinburne University of Technology, Astrophysics and Supercomputing, Hawthorn, Victoria 3122, Australia 3 P. Universidad Catolica,´ Departamento de Astronom´ıa y Astrof´ısica, Casilla 104, Santiago 22, Chile 4 Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA Received 5 November 1999 / Accepted 27 January 2000 Abstract. Prompted by a new catalogue of M31 globular clus- al. 1995; Minniti et al. 1996). Furthermore Hubble Space Tele- ters, we have collected together individual metallicity values for scope studies of merging disk galaxies reveal evidence for the globular clusters in the Local Group. Although we briefly de- GC systems of the progenitor galaxies (e.g. Forbes & Hau 1999; scribe the globular cluster systems of the individual Local Group Whitmore et al. 1999). Thus GCs should survive the merger of galaxies, the main thrust of our paper is to examine the collec- their parent galaxies, and will form a new GC system around tive properties. In this way we are simulating the dissipationless the newly formed elliptical galaxy. merger of the Local Group, into presumably an elliptical galaxy. The globular clusters of the Local Group are the best studied Such a merger is dominated by the Milky Way and M31, which and offer a unique opportunity to examine their collective prop- appear to be fairly typical examples of globular cluster systems erties (reviews of LG star clusters can be found in Brodie 1993 of spiral galaxies.
    [Show full text]
  • A Catalog of OB Associations in the Spiral Galaxy NGC 300 Presented in Sect
    Astronomy & Astrophysics manuscript no. (will be inserted by hand later) A Catalog of OB Associations in the spiral galaxy NGC 300 ⋆ G. Pietrzy´nski1,⋆⋆ W. Gieren1 P. Fouqu´e2,3 F. Pont4 1 Universidad de Concepci´on, Departamento de Fisica, Casilla 160–C, Concepci´on, Chile e-mail: [email protected], [email protected] 2 Observatoire de Paris-Meudon DESPA, F-92195 Meudon CEDEX, France 3 European Southern Observatory, Casilla 19001, Santiago 19, Chile e-mail: [email protected] 4 Universidad de Chile, Departamento de Astronomia, Casilla 36D, Santiago, Chile e-mail: [email protected] Abstract. We present results of a search for OB associations in NGC 300. Using an automatic and objective method (PLC technique) 117 objects were found. Statistical tests indicate that our sample is contaminated by less than 10 detections due to random concentrations of blue stars. Spatial distributions of detected associations and H II regions are strongly correlated. The size distribution reveals a significant peak at about 60 µrad which corresponds to 125 parsecs if a distance modulus of 26.66 mag is assumed. Besides the objects with sizes corresponding to typical associations we also found several much larger objects. A second level application of our detection method revealed that most of these are composed of smaller subgroups, with sizes of about 100 pc. Key words. galaxies: NGC 300: star clusters – galaxies: stellar content – stars: early type 1. Introduction As a result of these limitations it was not possible to per- form unambiguous comparisons of the properties of stellar OB associations constitute physical groups of young, mas- associations found in different galaxies.
    [Show full text]
  • Extraplanar HII Regions in the Edge-On Spiral Galaxies NGC 3628 and NGC 4522? Y
    A&A 605, A5 (2017) DOI: 10.1051/0004-6361/201730589 Astronomy & c ESO 2017 Astrophysics Extraplanar HII regions in the edge-on spiral galaxies NGC 3628 and NGC 4522? Y. Stein1, D. J. Bomans1; 2, A. M. N. Ferguson3, and R.-J. Dettmar1; 2 1 Astronomisches Institut (AIRUB), Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany e-mail: [email protected] 2 Research Department: Plasmas with Complex Interactions, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany 3 Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK Received 9 February 2017 / Accepted 30 May 2017 ABSTRACT Context. Gas infall and outflow are critical for determining the star formation rate and chemical evolution of galaxies but direct measurements of gas flows are difficult to make. Young massive stars and Hii regions in the halos of galaxies are potential tracers for accretion and/or outflows of gas. Aims. Gas phase abundances of three Hii regions in the lower halos of the edge-on galaxies NGC 3628 and NGC 4522 are determined by analyzing optical long-slit spectra. The observed regions have projected distances to the midplane of their host from 1.4 to 3 kpc. Methods. With the measured flux densities of the optical nebular emission lines, we derived the oxygen abundance 12 + log(O/H) for the three extraplanar Hii regions. The analysis was based on one theoretical and two empirical strong-line calibration methods. Results. The resulting oxygen abundances of the extraplanar Hii regions are comparable to the disk Hii regions in one case and are a little lower in the other case.
    [Show full text]
  • Tracing the Outer Disk of NGC 300: an Ultraviolet View
    J. Astrophys. Astr. (2019) 40:35 © Indian Academy of Sciences https://doi.org/10.1007/s12036-019-9603-4 Tracing the outer disk of NGC 300: An ultraviolet view CHAYAN MONDAL1,2,∗ , ANNAPURNI SUBRAMANIAM1 and KOSHY GEORGE3 1Indian Institute of Astrophysics, 2nd Block, Koramangala, Bengaluru 560 034, India. 2Pondicherry University, R.V. Nagar, Kalapet 605 014, India. 3Department of Physics, Christ University, Bengaluru, India. ∗Corresponding author. E-mail: [email protected] MS received 12 March 2019; accepted 11 July 2019 Abstract. We present an ultra-violet (UV) study of the galaxy NGC 300 using GALEX far-UV (FUV) and near-UV (NUV) observations. We studied the nature of UV emission in the galaxy and correlated it with optical, H I and mid-infrared (3.6 μm) wavelengths. Our study identified extended features in the outer disk, with the UV disk extending up to a radius of 12 kpc (>2R25). We estimated the FUV and NUV disk scale-length as 3.05 ± 0.27 kpc and 2.66 ± 0.20 kpc respectively. The scale-length in FUV is 2.3 times larger than that at 3.6 μm, and we also find the disk to gradually become flatter from longer to shorter wavelengths. We performed a statistical source subtraction to eliminate the background contaminants and identified 261 unresolved UV sources between the radii 5.3 kpc and 10 kpc (1 ∼ 2R25). The identified UV sources show an age range between 1–300 Myr with a peak at 25 Myr and a mass range between 103 M to 106 M, estimated using Starburst99 models.
    [Show full text]
  • Thick Disks and Halos of Spiral Galaxies M 81, NGC 55 and NGC 300
    A&A 431, 127–142 (2005) Astronomy DOI: 10.1051/0004-6361:20047042 & c ESO 2005 Astrophysics Thick disks and halos of spiral galaxies M 81, NGC 55 and NGC 300 N. A. Tikhonov1,2, O. A. Galazutdinova1,2, and I. O. Drozdovsky3,4 1 Special Astrophysical Observatory, Russian Academy of Sciences, N. Arkhyz, KChR 369167, Russia e-mail: [email protected] 2 Isaac Newton Institute of Chile, SAO Branch, Russia 3 Spitzer Science Center, Caltech, MC 220-6, Pasadena, CA 91125, USA 4 Astronomical Institute, St. Petersburg University, 198504, Russia Received 9 January 2004 / Accepted 28 September 2004 Abstract. By using images from the HST/WFPC2/ACS archive, we have analyzed the spatial distribution of the AGB and RGB stars along the galactocentric radius of nearby spiral galaxies M 81, NGC 300 and NGC 55. Examining color–magnitude diagrams and stellar luminosity functions, we gauge the stellar contents of the surroundings of the three galaxies. The red giant population (RGB) identified at large galactocentric radii yields a distance of 3.85 ± 0.08 Mpc for M 81, 2.12 ± 0.10 Mpc for NGC 55, and 2.00±0.13 Mpc for NGC 300, and a mean stellar metallicity of −0.65, −1.25, and −0.87 respectively. We find that there are two number density gradients of RGB stars along the radius, which correspond to the thick disk and halo components of the galaxies. We confirm the presence of a metallicity gradient of evolved stars in these galaxies, based on the systematic changes of the color distribution of red giant stars.
    [Show full text]
  • Caldwell Catalogue - Wikipedia, the Free Encyclopedia
    Caldwell catalogue - Wikipedia, the free encyclopedia Log in / create account Article Discussion Read Edit View history Caldwell catalogue From Wikipedia, the free encyclopedia Main page Contents The Caldwell Catalogue is an astronomical catalog of 109 bright star clusters, nebulae, and galaxies for observation by amateur astronomers. The list was compiled Featured content by Sir Patrick Caldwell-Moore, better known as Patrick Moore, as a complement to the Messier Catalogue. Current events The Messier Catalogue is used frequently by amateur astronomers as a list of interesting deep-sky objects for observations, but Moore noted that the list did not include Random article many of the sky's brightest deep-sky objects, including the Hyades, the Double Cluster (NGC 869 and NGC 884), and NGC 253. Moreover, Moore observed that the Donate to Wikipedia Messier Catalogue, which was compiled based on observations in the Northern Hemisphere, excluded bright deep-sky objects visible in the Southern Hemisphere such [1][2] Interaction as Omega Centauri, Centaurus A, the Jewel Box, and 47 Tucanae. He quickly compiled a list of 109 objects (to match the number of objects in the Messier [3] Help Catalogue) and published it in Sky & Telescope in December 1995. About Wikipedia Since its publication, the catalogue has grown in popularity and usage within the amateur astronomical community. Small compilation errors in the original 1995 version Community portal of the list have since been corrected. Unusually, Moore used one of his surnames to name the list, and the catalogue adopts "C" numbers to rename objects with more Recent changes common designations.[4] Contact Wikipedia As stated above, the list was compiled from objects already identified by professional astronomers and commonly observed by amateur astronomers.
    [Show full text]
  • The PNLF Distance to the Sculptor Group Galaxy NGC 55
    The PNLF distance to the Sculptor Group galaxy NGC 55 G. C. Van de Steene1, G. H. Jacoby2, C. Praet3, R. Ciardullo4, and H. Dejonghe3 1 Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium 2 WIYN Observatory, PO Box 26732, Tucson, AZ, 85726, USA 3 Universiteit Gent, Krijgslaan 281 (S9), 9000 Gent, Belgium 4 Department of Astronomy and Astrophysics, Penn State University, 525 Davey Lab University Park, PA 16802, USA Abstract. We identified 21 new Planetary Nebula (PN) candidates in the Sculptor Group galaxy NGC 55. We determined a most likely distance of 2.00 ± 0.2 Mpc using the Planetary Nebulae Luminosity Function (PNLF) method. The distance to NGC 55 is larger than previously determined distances, which means that the Sculptor Group is a bit further away from the Local Group than previously thought. The distance to NGC 55 is again similar to the distance of NGC 300, adding support to the suggestion that these galaxies form a bound pair. 1 NGC55 NGC 55 is a highly inclined (i=85±5◦) late type galaxy (SB(s)m) in the Sculptor ′ Group. Its Holmberg radius is 20.2 and blue magnitude mB =8.42. Sculptor is a very loosely concentrated and almost freely expanding aggregate of galaxies of prolate shape which we view pole-on. It stretches from the outskirts of the Local Group at 1.5 Mpc out to 5 Mpc. Besides the 5 main spiral galaxies, the Sculptor Group contains several dwarf galaxies (Jerjen et al. [1998]). NGC 55 is one of the 5 bright spiral galaxies of the Sculptor Group, which could be the one nearest to the Milky Way.
    [Show full text]
  • Is NGC 300 a Pure Exponential Disk Galaxy?
    University of Louisville ThinkIR: The University of Louisville's Institutional Repository Faculty Scholarship 8-1-2020 Is NGC 300 a pure exponential disk galaxy? In Sung Jang Leibniz Institute for Astrophysics Potsdam Roelof S. De Jong Leibniz Institute for Astrophysics Potsdam Ivan Minchev Leibniz Institute for Astrophysics Potsdam Eric F. Bell University of Michigan, Ann Arbor Antonela Monachesi Universidad de La Serena See next page for additional authors Follow this and additional works at: https://ir.library.louisville.edu/faculty Part of the Astrophysics and Astronomy Commons ThinkIR Citation Jang, In Sung; De Jong, Roelof S.; Minchev, Ivan; Bell, Eric F.; Monachesi, Antonela; Holwerda, Benne W.; Bailin, Jeremy; Smercina, Adam; and D'Souza, Richard, "Is NGC 300 a pure exponential disk galaxy?" (2020). Faculty Scholarship. 474. https://ir.library.louisville.edu/faculty/474 This Article is brought to you for free and open access by ThinkIR: The University of Louisville's Institutional Repository. It has been accepted for inclusion in Faculty Scholarship by an authorized administrator of ThinkIR: The University of Louisville's Institutional Repository. For more information, please contact [email protected]. Authors In Sung Jang, Roelof S. De Jong, Ivan Minchev, Eric F. Bell, Antonela Monachesi, Benne W. Holwerda, Jeremy Bailin, Adam Smercina, and Richard D'Souza This article is available at ThinkIR: The University of Louisville's Institutional Repository: https://ir.library.louisville.edu/ faculty/474 A&A 640, L19 (2020) Astronomy https://doi.org/10.1051/0004-6361/202038651 & c ESO 2020 Astrophysics LETTER TO THE EDITOR Is NGC 300 a pure exponential disk galaxy? In Sung Jang1, Roelof S.
    [Show full text]
  • Arxiv:1310.6365V2 [Astro-Ph.CO] 29 Oct 2013
    Astronomy & Astrophysics manuscript no. pap3109_v2 c ESO 2018 September 13, 2018 Letter to the Editor Dwarfs walking in a row. The filamentary nature of the NGC 3109 association. M. Bellazzini1, T. Oosterloo2; 3, F. Fraternali4; 3, and G. Beccari5 1 INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy e-mail: [email protected] 2 Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands 3 Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, The Netherlands 4 Dipartimento di Fisica e Astronomia - Università degli Studi di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy 5 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei Munchen, Germany Accepted for publication by A&A. Submitted on September 24, 2013. ABSTRACT We re-consider the association of dwarf galaxies around NGC 3109, whose known members were NGC 3109, Antlia, Sextans A, and Sextans B, based on a new updated list of nearby galaxies and the most recent data. We find that the original members of the NGC 3109 association, together with the recently discovered and adjacent dwarf irregular Leo P, form a very tight and elongated configuration in space. All these galaxies lie within ∼ 100 kpc of a line that is ' 1070 kpc long, from one extreme (NGC 3109) to the other (Leo P), and they show a gradient in the Local Group standard of rest velocity with a total amplitude of 43 km s−1 Mpc−1, and a r.m.s. scatter of just 16.8 km s−1. It is shown that the reported configuration is exceptional given the known dwarf galaxies in the Local Group and its surroundings.
    [Show full text]
  • A Catalog of OB Associations in the Spiral Galaxy NGC 300?
    A&A 371, 497–506 (2001) Astronomy DOI: 10.1051/0004-6361:20010401 & c ESO 2001 Astrophysics A Catalog of OB Associations in the spiral galaxy NGC 300? G. Pietrzy´nski1,5,W.Gieren1,P.Fouqu´e2,3,andF.Pont4 1 Universidad de Concepci´on, Departamento de Fisica, Casilla 160–C, Concepci´on, Chile e-mail: [email protected] 2 Observatoire de Paris-Meudon DESPA, 92195 Meudon Cedex, France 3 European Southern Observatory, Casilla 19001, Santiago 19, Chile e-mail: [email protected] 4 Universidad de Chile, Departamento de Astronomia, Casilla 36D, Santiago, Chile e-mail: [email protected] 5 Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland Received 2 January 2001 / Accepted 13 March 2001 Abstract. We present results of a search for OB associations in NGC 300. Using an automatic and objective method (PLC technique) 117 objects were found. Statistical tests indicate that our sample is contaminated by less than 10 detections due to random concentrations of blue stars. Spatial distributions of detected associations and H II regions are strongly correlated. The size distribution reveals a significant peak at about 60 µrad which corresponds to 125 parsecs if a distance modulus of 26.66 mag is assumed. Besides the objects with sizes corresponding to typical associations we also found several much larger objects. A second level application of our detection method revealed that most of these are composed of smaller subgroups, with sizes of about 100 pc. Key words. galaxies: NGC 300: star clusters – galaxies: stellar content – stars: early type 1. Introduction resolution often led to disagreement between different au- thors.
    [Show full text]
  • The Structure & Stellar Populations of Nuclear Star Clusters in Late-Type
    UC Irvine UC Irvine Electronic Theses and Dissertations Title The Structure and Stellar Populations of Nuclear Star Clusters in Late-Type Spiral Galaxies Permalink https://escholarship.org/uc/item/3634g66n Author Carson, Daniel James Publication Date 2016 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA, IRVINE The Structure & Stellar Populations of Nuclear Star Clusters in Late-Type Spiral Galaxies DISSERTATION submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in Physics by Daniel J. Carson Dissertation Committee: Professor Aaron Barth, Chair Associate Professor Michael Cooper Professor James Bullock 2016 Portion of Chapter 1 c 2015 The Astronomical Journal Chapter 2 c 2015 The Astronomical Journal Chapter 3 c 2015 The Astronomical Journal Portion of Chapter 5 c 2015 The Astronomical Journal All other materials c 2016 Daniel J. Carson TABLE OF CONTENTS Page LIST OF FIGURES iv LIST OF TABLES vi ACKNOWLEDGMENTS vii CURRICULUM VITAE viii ABSTRACT OF THE DISSERTATION x 1 Introduction 1 2 HST /WFC3 data 9 2.1 SampleSelection ................................. 9 2.2 DescriptionofObservations . 10 2.3 DataReduction.................................. 14 3 Analysis of Structural Properties 17 3.1 Surface Brightness Profile Fitting . 17 3.1.1 PSFModels................................ 18 3.1.2 FittingMethod .............................. 19 3.1.3 Comparison with ISHAPE ......................... 21 3.1.4 1DRadialProfiles ............................ 22 3.1.5 Uncertainties in Cluster Parameters . 25 3.2 Results....................................... 29 3.2.1 SingleBandResults ........................... 29 3.2.2 PanchromaticResults........................... 40 3.2.3 Stellar Populations . 46 3.3 CommentsonIndividualObjects . 51 3.3.1 IC342................................... 51 3.3.2 M33 ...................................
    [Show full text]