The Population of Pulsating Variable Stars in the Sextans Dwarf Spheroidal Galaxy

被引:22
作者
Katherina Vivas, A. [1 ]
Alonso-Garcia, Javier [2 ,3 ]
Mateo, Mario [4 ]
Walker, Alistair [1 ]
Howard, Brittany [5 ]
机构
[1] Natl Opt Astron Observ, Cerro Tololo Interamer Observ, Casilla 603, La Serena, Chile
[2] Univ Antofagasta, Ctr Astron CITEVA, Av Angamos 601, Antofagasta, Chile
[3] Inst Milenio Astrofis, Santiago, Chile
[4] Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA
[5] Univ Victoria, Dept Phys & Astron, POB 1700 STN CSC, Victoria, BC V8W 2Y2, Canada
基金
英国科学技术设施理事会; 美国国家航空航天局; 美国国家科学基金会;
关键词
galaxies: dwarf; galaxies: individual (Sextans); galaxies:stellar content; stars: variables: general; stars: variables: RR Lyrae; RR-LYRAE STARS; LOCAL GROUP GALAXIES; DELTA-SCUTI STARS; CCD PHOTOMETRY; MILKY-WAY; DISCOVERY; CATALOG;
D O I
10.3847/1538-3881/aaf4f3
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
A large extension of the Sextans dwarf spheroidal galaxy, 7 deg(2), has been surveyed for variable stars using the Dark Energy Camera at the Blanco Telescope at Cerro Tololo Inter-American Observatory, Chile. We report seven anomalous Cepheids, 199 RR Lyrae stars, and 16 dwarf Cepheids in the field. This is only the fifth extragalactic system in which dwarf Cepheids have been systematically searched. Henceforth, the new stars increase the census of stars coming from different environments that can be used to asses the advantages and limitations of using dwarf Cepheids as standard candles in populations for which the metallicity is not necessarily known. The dwarf Cepheids found in Sextans have a mean period of 0.066 day and a mean g amplitude of 0.87 mag. They are located below the horizontal branch, spanning a range of 0.8 mag: 21.9 < g < 22.7. The number of dwarf Cepheids in Sextans is low compared with other galaxies such as Carina, which has a strong intermediate-age population. On the other hand, the number and ratio of RR Lyrae stars to dwarf Cepheids are quite similar to those of Sculptor, a galaxy which, as Sextans, is dominated by an old stellar population. The dwarf Cepheid stars found in Sextans follow a well-constrained period-luminosity relationship with an rms = 0.05 mag in the g band, which was set up by anchoring to the distance modulus given by the RR Lyrae stars. Although the majority of the variable stars in Sextans are located toward the center of the galaxy, we have found two RR Lyrae stars and one anomalous Cepheid in the outskirts of the galaxy that may be extratidal stars and suggest that this galaxy may be undergoing tidal destruction. These possible extratidal variable stars share the same proper motions as Sextans, as seen by recent Gaia measurements. Two additional stars that we initially classified as foreground RR Lyrae stars may actually be other examples of Sextans extratidal anomalous Cepheids, although radial velocities are needed to prove that scenario.
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页数:17
相关论文
共 61 条
[1]   UNCLOAKING GLOBULAR CLUSTERS IN THE INNER GALAXY [J].
Alonso-Garcia, Javier ;
Mateo, Mario ;
Sen, Bodhisattva ;
Banerjee, Moulinath ;
Catelan, Marcio ;
Minniti, Dante ;
von Braun, Kaspar .
ASTRONOMICAL JOURNAL, 2012, 143 (03)
[2]  
Amigo P., 2012, THESIS
[3]  
[Anonymous], 2016, Astronomy and Astrophysics, DOI [DOI 10.1051/0004-6361/201629272, 10.1051/0004-6361/201629272], Patent No. [2016a,A&A,595,A1, 2016595]
[4]  
[Anonymous], 2016, ARXIV161205242
[5]   A search for SX Phe stars among Kepler δ Scuti stars [J].
Balona, L. A. ;
Nemec, J. M. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2012, 426 (03) :2413-2418
[6]   Study of the Sextans dwarf spheroidal galaxy from the DART Ca ii triplet survey☆ [J].
Battaglia, G. ;
Tolstoy, E. ;
Helmi, A. ;
Irwin, M. ;
Parisi, P. ;
Hill, V. ;
Jablonka, P. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2011, 411 (02) :1013-1034
[7]  
Breger M, 2000, ASTR SOC P, V210, P3
[8]   Gaia Data Release 2. Summary of the contents and survey properties [J].
Brown, A. G. A. ;
Vallenari, A. ;
Prusti, T. ;
de Bruijne, J. H. J. ;
Babusiaux, C. ;
Bailer-Jones, C. A. L. ;
Biermann, M. ;
Evans, D. W. ;
Eyer, L. ;
Jansen, F. ;
Jordi, C. ;
Klioner, S. A. ;
Lammers, U. ;
Lindegren, L. ;
Luri, X. ;
Mignard, F. ;
Panem, C. ;
Pourbaix, D. ;
Randich, S. ;
Sartoretti, P. ;
Siddiqui, H. I. ;
Soubiran, C. ;
van Leeuwen, F. ;
Walton, N. A. ;
Arenou, F. ;
Bastian, U. ;
Cropper, M. ;
Drimmel, R. ;
Katz, D. ;
Lattanzi, M. G. ;
Bakker, J. ;
Cacciari, C. ;
Castaneda, J. ;
Chaoul, L. ;
Cheek, N. ;
De Angeli, F. ;
Fabricius, C. ;
Guerra, R. ;
Holl, B. ;
Masana, E. ;
Messineo, R. ;
Mowlavi, N. ;
Nienartowicz, K. ;
Panuzzo, P. ;
Portell, J. ;
Riello, M. ;
Seabroke, G. M. ;
Tanga, P. ;
Thevenin, F. ;
Gracia-Abril, G. .
ASTRONOMY & ASTROPHYSICS, 2018, 616
[9]  
Catelan M, 2015, PULSATING STARS
[10]   Tracing the stellar component of low surface brightness Milky Way dwarf galaxies to their outskirts [J].
Cicuendez, L. ;
Battaglia, G. ;
Irwin, M. ;
Bermejo-Climent, J. R. ;
McMonigal, B. ;
Bate, N. F. ;
Lewis, G. F. ;
Conn, A. R. ;
de Boer, T. J. L. ;
Gallart, C. ;
Guglielmo, M. ;
Ibata, R. ;
McConnachie, A. ;
Tolstoy, E. ;
Fernando, N. .
ASTRONOMY & ASTROPHYSICS, 2018, 609