A DECam view of the diffuse dwarf galaxy Crater II - Variable stars

A. Katherina Vivas, Alistair R. Walker, Clara E. Martinez-Vazquez, Matteo Monelli, Giuseppe Bono, Antonio Dorta, David L. Nidever, Giuliana Fiorentino, Carme Gallart, Gloria Andreuzzi, Vittorio F. Braga, Massimo Dall'Ora, Knut Olsen, Peter B. Stetson

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4 Citas (Scopus)

Resumen

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.

Idioma originalInglés
Páginas (desde-hasta)1061-1077
Número de páginas17
PublicaciónMonthly Notices of the Royal Astronomical Society
Volumen492
N.º1
DOI
EstadoPublicada - 1 feb 2020

Áreas temáticas de ASJC Scopus

  • Astronomía y astrofísica
  • Ciencias planetarias y espacial

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