Bibcode
Martínez-Vázquez, C. E.; Monelli, M.; Bono, G.; Stetson, P. B.; Ferraro, I.; Bernard, E. J.; Gallart, C.; Fiorentino, G.; Iannicola, G.; Udalski, A.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 454, Issue 2, p.1509-1516
Advertised on:
12
2015
Citations
54
Refereed citations
44
Description
We identified and characterized the largest (536) RR Lyrae (RRL) sample
in a Milky Way dSph satellite (Sculptor) based on optical photometry
data collected over ˜24 years. The RRLs display a spread in
V-magnitude (˜0.35 mag) which appears larger than photometric
errors and the horizontal branch (HB) luminosity evolution of a
mono-metallic population. Using several calibrations of two different
reddening free and metal independent period-Wesenheit relations we
provide a new distance estimate μ = 19.62 mag (σμ
= 0.04 mag) that agrees well with literature estimates. We constrained
the metallicity distribution of the old population, using the
MI period-luminosity relation, and we found that it ranges
from -2.3 to -1.5 dex. The current estimate is narrower than suggested
by low and intermediate spectroscopy of RGBs (Δ [Fe/H]≤ 1.5).
We also investigated the HB morphology as a function of the
galactocentric distance. The HB in the innermost regions is dominated by
red HB stars and by RRLs, consistent with a more metal-rich population,
while in the outermost regions it is dominated by blue HB stars and RRLs
typical of a metal-poor population. Our results suggest that fast
chemical evolution occurred in Sculptor, and that the radial gradients
were in place at an early epoch.
Related projects
Galaxy Evolution in the Local Group
Galaxy formation and evolution is a fundamental Astrophysical problem. Its study requires “travelling back in time”, for which there are two complementary approaches. One is to analyse galaxy properties as a function of red-shift. Our team focuses on the other approach, called “Galactic Archaeology”. It is based on the determination of galaxy
Matteo
Monelli