2001/03/30 by A. Bragaglia, R. Gratton, R. G. Gratton +4 · 36 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Distance modulus #Galaxy #Globular cluster #Horizontal branch #Large Magellanic Cloud #Metallicity #Physics #RR Lyrae variable #Red-giant branch #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/321116
published in The Astronomical Journal 122(1), 207-219 (Institute of Physics) · 33 pages, 7 figures, uses aastex, accepted for publication in AJ
arxiv created 2001/03/30 · openalex publication_date 2001/07/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Metallicities for six double-mode RR Lyrae stars (RR d 's) in the Large Magellanic Cloud have been estimated using the Δ S method. The derived [Fe/H] values are in the range [Fe/H] = -1.09 to -1.78 (or -0.95 to -1.58, adopting a different calibration of [Fe/H] versus Δ S ). Two stars in our sample are at the very metal-rich limit of all RR d 's for which metal abundance has been estimated, either by direct measure (for field objects) or on the basis of the hosting system (for objects in globular clusters or external galaxies). These metal abundances, coupled with mass determinations from pulsational models and the Petersen diagram, are used to compare the mass-metallicity distribution of field and cluster RR Lyrae variables. We find that field and cluster RR d 's seem to follow the same mass-metallicity distribution, within the observational errors, strengthening the case for uniformity of properties between field and cluster variables. At odds to what is usually assumed, we find no significant difference in mass for RR Lyrae variables in globular clusters of different metallicity and Oosterhoff types, or there may even be a difference contrary to the commonly accepted one, depending on the metallicity scale adopted to derive the masses. This "unusual" result for the mass-metallicity relation is probably due, at least in part, to the inclusion of updated opacity tables in the computation of metal-dependent pulsation models.