2000/01/31 by Eugenio Carretta, E. Carretta, Raffaele Gratton +3 · 19 citations
Physics and Astronomy · #Absolute magnitude #Astronomy and Astrophysical Research #Cluster (spacecraft) #Field (mathematics) #Globular cluster #History and Developments in Astronomy #Horizontal branch #Luminosity #RR Lyrae variable #Star cluster #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2000.03398.x
published in Monthly Notices of the Royal Astronomical Society 316(4), 721-728 (Oxford University Press) · 8 pages, 5 encapsulated figures, LaTeX, uses mn.sty. Accepted by MNRAS
arxiv created 2000/01/31 · openalex publication_date 2000/08/21 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The discrepancy between a LONG distance scale derived from Hipparcos based distances to globular clusters via main sequence fitting to local subdwarfs, and a SHORT distance scale derived from the absolute magnitude of field RR Lyraes via statistical parallaxes and the Baade-Wesselink method could be accounted for whether an intrinsic difference of about 0.1-0.2 mag was found to exist between horizontal branch (HB) stars populating the "sparse" general field and the "dense" globular clusters. In this paper we discuss the possible existence of such a systematic difference comparing the "period-shifts" observed for field and cluster RR Lyraes. Various approaches based on different parameters and data-sets for both cluster and field variables were used in order to establish the size of such a hypothetical difference, if any. We find that on the whole very small not significant differences exist between the period-metallicity distributions of field and cluster RR Lyraes, thus confirming with a more quantitative approach, the qualitative conclusions by Catelan (1998). This observational evidence translates into a very small difference between the horizontal branch luminosity of field and cluster stars, unless RR Lyraes in Globular Clusters are about 0.06 Mo more massive than field RR Lyrae at same metallicity, which is to be proven.