Physical Sciences and Mathematics Commons^™

Individual Element Sensitivity For Stellar Evolutionary Isochrones, Guy Worthey, Xiang Shi, Tathagata Pal, Hyun-Chul Lee, Baitian Tang

Physics and Astronomy Faculty Publications and Presentations

Stellar evolution calculations with variable abundance ratios were used to gauge the effects on temperatures, luminosities, and lifetimes in various phases. The individual elements C, N, O, Mg, Si, and Fe were included. Most of the effect relevant to integrated light models is contained in the temperature variable, as opposed to the time-scale or luminosity. We derive a recipe for including abundance-sensitive temperature effects that is applicable to existing isochrone grids. The resultant enhanced isochrones are incorporated into composite stellar population models and compared with galaxy data from the Sloan Digital Sky Survey. A severe oxygen–age degeneracy is apparent, 2–3 …