Variable stars in local group galaxies - IV. RR Lyrae stars in the central regions of the low-density galaxy Crater II - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2018

Variable stars in local group galaxies - IV. RR Lyrae stars in the central regions of the low-density galaxy Crater II

M. Monelli
A. R. Walker
  • Function : Author
C. E. Martínez-Vázquez
  • Function : Author
P. B. Stetson
  • Function : Author
C. Gallart
  • Function : Author
G. Bono
  • Function : Author
A. K. Vivas
  • Function : Author
G. Andreuzzi
  • Function : Author
M. Dall'Ora
  • Function : Author
G. Fiorentino
A. Dorta
  • Function : Author

Abstract

We present a search and analysis of variable stars in the recently discovered Crater II dwarf galaxy. Based on B, V, I data collected with the Isaac Newton Telescope (FoV∼0.44 deg2), we detected 37 variable stars, of which 34 are bone-fide RR Lyrae stars of Crater II (28 RRab, 4 RRc, 2 RRd). We applied the metal-independent (V, B - V) Period-Wesenheit relation and derived a true distance modulus (μ = 20.30 ± 0.08 mag (σ = 0.16 mag). Individual metallicities for RR Lyrae stars were derived by inversion of the predicted I-band Period-Luminosity relation. We find a mean metallicity of [Fe/H] = -1.64 and a standard deviation of σ _{[Fe/H]}=0.21 dex, compatible with either negligible or vanishing intrinsic metallicity dispersion. The analysis of the colour-magnitude diagram reveals a stark paucity of blue horizontal branch stars, at odds with other Galactic dwarfs, and globular clusters with similar metal abundances.
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Dates and versions

insu-03689234 , version 1 (07-06-2022)

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M. Monelli, A. R. Walker, C. E. Martínez-Vázquez, P. B. Stetson, C. Gallart, et al.. Variable stars in local group galaxies - IV. RR Lyrae stars in the central regions of the low-density galaxy Crater II. Monthly Notices of the Royal Astronomical Society, 2018, 479, pp.4279-4291. ⟨10.1093/mnras/sty1645⟩. ⟨insu-03689234⟩
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