2003/04/03 by G. Clementini, E. V. Held, L. Baldacci +1 · 2 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/375633
14 pages, 3 figures, Ap.J.L., in press, May 10 issue
arxiv created 2003/04/03 · openalex publication_date 2003/04/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We report the discovery of a large number of short-period variable stars in the dwarf irregular galaxy NGC 6822, based on deep time-series imaging carried out with the ESO Very Large Telescope. In particular, we found a modest population of RR Lyrae stars tracing the presence of an old stellar component in NGC 6822. Measurements of the average luminosity of RR Lyrae stars provide a new independent estimate of the distance to this galaxy based on a Population II indicator, ( m - M ) 0 = 23.36 ± 0.17. In addition, our new data show a significant population of small-amplitude, short-period variable stars filling the instability strip starting at luminosities only a few tenths of a magnitude brighter than the RR Lyrae stars. Given the presence of an extended star formation in NGC 6822, the faint end of this distribution of short-period variable stars is likely to originate from a population of intermediate-age, metal-poor He-burning stars, younger and more massive than RR Lyrae stars.