1999/06/08 by W. Landsman, Landsman, W.
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9906123
4 pages, contributed talk at the meeting "Spectrophotometric Dating of Stars and Galaxies", Annapolis, USA, May 1999
arxiv created 1999/06/08 · openalex publication_date 1999/06/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
There is now considerable evidence that horizontal branch (HB) stars hotter than about 11,500 K experience an enormous enhancement of their photospheric iron abundance due to radiative levitation. In globular clusters, the photospheric iron abundance can reach values of [Fe/H] ~ +0.3, or up to two orders of magnitude higher than the cluster iron abundance. Model atmospheres which take into account the iron overabundance are needed for understanding the appearance of the HB in globular cluster color-magnitude diagrams (CMDs), for the derivation of accurate luminosities, gravities and masses, and for the ultraviolet spectral synthesis of old, metal-poor stellar populations.