2005/12/20 by Stephan R. Bjork, Brian Chaboyer
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/500505
published as Astrophys.J.641:1102-1112,2006 · 30 pages, 6 figures. To appear in ApJ
arxiv created 2005/12/20 · openalex publication_date 2006/04/14 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
A Monte Carlo simulation exploring uncertainties in standard stellar evolution theory on the red giant branch of metal-poor globular clusters has been conducted. Confidence limits are derived on the absolute V -band magnitude of the bump in the red giant branch luminosity function ( M V,b ) and the excess number of stars in the bump, R b . The analysis takes into account uncertainties in the primordial helium abundance, abundance of α-capture elements, radiative and conductive opacities, nuclear reaction rates, neutrino energy losses, the treatments of diffusion and convection, the surface boundary conditions, and color transformations. The uncertainty in theoretical values for the red giant bump magnitude varies with metallicity between +0.13 and -0.12 mag at [Fe/H] = -2.4 and between +0.23 and -0.21 mag at [Fe/H] = -1.0. The dominant sources of uncertainty are the abundance of the α-capture elements , the mixing length, and the low-temperature opacities. The theoretical values of M V,b are in good agreement with observations. The uncertainty in the theoretical value of R b is ±0.01 at all metallicities studied. The dominant sources of uncertainty are the abundance of the α-capture elements, the mixing length, and the high-temperature opacities. The median value of R b varies from 0.44 at [Fe/H] = -2.4 to 0.50 at [Fe/H] = -1.0. These theoretical values for R b are in agreement with observations.