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Title: A DECam view of the diffuse dwarf galaxy Crater II – Variable stars

Abstract

ABSTRACT Time series observations of a single dithered field centred on the diffuse dwarf satellite galaxy Crater II were obtained with the Dark Energy Camera (DECam) at the 4m Blanco Telescope at Cerro Tololo Inter-American Observatory, Chile, uniformly covering up to two half-light radii. Analysis of the g and i time series results in the identification and characterization of 130 periodic variable stars, including 98 RR Lyrae stars, 7 anomalous Cepheids, and 1 SX Phoenicis star belonging to the Crater II population, and 24 foreground variables of different types. Using the large number of ab-type RR Lyrae stars present in the galaxy, we obtained a distance modulus to Crater II of (m − M)0 = 20.333 ± 0.004 (stat) ±0.07 (sys). The distribution of the RR Lyrae stars suggests an elliptical shape for Crater II, with an ellipticity of 0.24 and a position angle of 153°. From the RR Lyrae stars, we infer a small metallicity dispersion for the old population of Crater II of only 0.17 dex. There are hints that the most metal-poor stars in that narrow distribution have a wider distribution across the galaxy, while the slightly more metal-rich part of the population is more centrally concentrated. Given the featuresmore » in the colour–magnitude diagram of Crater II, the anomalous Cepheids in this galaxy must have formed through a binary evolution channel of an old population.« less

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1]; ORCiD logo [2];  [3];  [2];  [4]; ORCiD logo [5];  [2];  [6]; ORCiD logo [7];  [8];  [9];  [10]
  1. Cerro Tololo Inter-American Observatory, NSF’s National Optical-Infrared Astronomy Research Laboratory, Casilla 603, La Serena, Chile
  2. Instituto de Astrofísica de Canarias, Calle Vía Láctea, E-38205 La Laguna, Tenerife, Spain, Universidad de La Laguna, Dpto. Astrofísica, E-38206 La Laguna, Tenerife, Spain
  3. Departimento di Fisica, Universitá di Roma Tor Vergata, via della Ricerca Scientifica 1, I-00133 Rome, Italy
  4. Department of Physics, Montana State University, PO Box 173840, Bozeman, MT 59717, USA, NSF’s National Optical-Infrared Astronomy Research Laboratory, 950 North Cherry Avenue, Tucson, AZ 85719, USA
  5. INAF – Osservatorio Astronomica di Bologna, via Ranzani 1, I-40127 Bologna, Italy
  6. INAF – Fundación Galileo Galilei, Rambla José Ana Fernandez Pérez 7, E-38712, Breña Baja, Spain, INAF – Osservatorio Astronomico di Roma, via Frascati 33, I-00040, Monte Porzio Catone (Roma), Italy
  7. Instituto Milenio de Astrofíisica, Ave. Vicuña Mackena 4860, 782-0436 Macul, Santiago, Chile, Departamento de Física, Facultad de Ciencias Exactas, Universidad Andrés Bello, Fernández Concha 700, Las Condes, Santiago, Chile
  8. INAF – Osservatorio Astronomica di Capodimonte, salita Moiariello 16, I-80131 Napoli, Italy
  9. NSF’s National Optical-Infrared Astronomy Research Laboratory, 950 North Cherry Avenue, Tucson, AZ 85719, USA
  10. Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council, Victoria, British Columbia V9E 2E7, Canada
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1581854
Resource Type:
Published Article
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Name: Monthly Notices of the Royal Astronomical Society Journal Volume: 492 Journal Issue: 1; Journal ID: ISSN 0035-8711
Publisher:
Oxford University Press
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Vivas, A. Katherina, Walker, Alistair R., Martínez-Vázquez, Clara E., Monelli, Matteo, Bono, Giuseppe, Dorta, Antonio, Nidever, David L., Fiorentino, Giuliana, Gallart, Carme, Andreuzzi, Gloria, Braga, Vittorio F., Dall’Ora, Massimo, Olsen, Knut, and Stetson, Peter B. A DECam view of the diffuse dwarf galaxy Crater II – Variable stars. United Kingdom: N. p., 2019. Web. doi:10.1093/mnras/stz3393.
Vivas, A. Katherina, Walker, Alistair R., Martínez-Vázquez, Clara E., Monelli, Matteo, Bono, Giuseppe, Dorta, Antonio, Nidever, David L., Fiorentino, Giuliana, Gallart, Carme, Andreuzzi, Gloria, Braga, Vittorio F., Dall’Ora, Massimo, Olsen, Knut, & Stetson, Peter B. A DECam view of the diffuse dwarf galaxy Crater II – Variable stars. United Kingdom. doi:10.1093/mnras/stz3393.
Vivas, A. Katherina, Walker, Alistair R., Martínez-Vázquez, Clara E., Monelli, Matteo, Bono, Giuseppe, Dorta, Antonio, Nidever, David L., Fiorentino, Giuliana, Gallart, Carme, Andreuzzi, Gloria, Braga, Vittorio F., Dall’Ora, Massimo, Olsen, Knut, and Stetson, Peter B. Wed . "A DECam view of the diffuse dwarf galaxy Crater II – Variable stars". United Kingdom. doi:10.1093/mnras/stz3393.
@article{osti_1581854,
title = {A DECam view of the diffuse dwarf galaxy Crater II – Variable stars},
author = {Vivas, A. Katherina and Walker, Alistair R. and Martínez-Vázquez, Clara E. and Monelli, Matteo and Bono, Giuseppe and Dorta, Antonio and Nidever, David L. and Fiorentino, Giuliana and Gallart, Carme and Andreuzzi, Gloria and Braga, Vittorio F. and Dall’Ora, Massimo and Olsen, Knut and Stetson, Peter B.},
abstractNote = {ABSTRACT Time series observations of a single dithered field centred on the diffuse dwarf satellite galaxy Crater II were obtained with the Dark Energy Camera (DECam) at the 4m Blanco Telescope at Cerro Tololo Inter-American Observatory, Chile, uniformly covering up to two half-light radii. Analysis of the g and i time series results in the identification and characterization of 130 periodic variable stars, including 98 RR Lyrae stars, 7 anomalous Cepheids, and 1 SX Phoenicis star belonging to the Crater II population, and 24 foreground variables of different types. Using the large number of ab-type RR Lyrae stars present in the galaxy, we obtained a distance modulus to Crater II of (m − M)0 = 20.333 ± 0.004 (stat) ±0.07 (sys). The distribution of the RR Lyrae stars suggests an elliptical shape for Crater II, with an ellipticity of 0.24 and a position angle of 153°. From the RR Lyrae stars, we infer a small metallicity dispersion for the old population of Crater II of only 0.17 dex. There are hints that the most metal-poor stars in that narrow distribution have a wider distribution across the galaxy, while the slightly more metal-rich part of the population is more centrally concentrated. Given the features in the colour–magnitude diagram of Crater II, the anomalous Cepheids in this galaxy must have formed through a binary evolution channel of an old population.},
doi = {10.1093/mnras/stz3393},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 1,
volume = 492,
place = {United Kingdom},
year = {2019},
month = {12}
}

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