The Y2 Isochrones Getting an Extra Dimension
Abstract
The Yonsei-Yale Isochrones have been widely used since its birth in 2001. We announce a major upgrade mainly making varieties of helium values available. The recent works on the globular clusters with extreme helium abundances have called for such a need. The new version of the Y2 Isochrones are available for [α/Fe] = 0 through 0.6, ΔY/ΔZ = 1.5 through 3.0, and extreme helium abundances (Y = normal 0.05, 0.1, 0.15, 0.2), and for 11 metallicity grids, with full capability of interpolation. The database will be powerful for making population models. Besides, the accuracy of the models on the lower main sequence has been substantially improved. We illustrate the major upgrades and demonstrate the power of the new grids.
- Publication:
-
The Art of Modeling Stars in the 21st Century
- Pub Date:
- October 2008
- DOI:
- 10.1017/S174392130802334X
- Bibcode:
- 2008IAUS..252..413Y