Stellar Models

As part of my posdoc position at UoA and UCSD I created a selection of stellar atmosphere models using ATLAS/SYNTHE and PHOENIX. I also created sets of stellar interior models using MESA. You can download these various models from this page

The models were created using low metallicities and non-standard compositions (i.e. not simply scaled-solar metallicities). Globular clusters have been shown to contain multiple populations with differing values of [C/Fe], [N/Fe] and [O/Fe] in addition to non-solar helium abundances, and we used these models to investigate the effect of these abundances on stellar evolution.

MESA models

I used MESA to create stellar interior models, with non-standard abundances. The resulting isochrones are available by following the links in the table below. The isochrones are at ages of 1, 5, and 13.5 Gyr, and extend from ~0.6 Msun to 0.04 Msun. The file names give the composition adopted, in the form mesa_fehm17_y040_cm010np030om01.iso, where fehm17 corresponds to [Fe/H]=-1.7, y040 denotes Y=0.40, cm01 denotes [C/Fe]=-0.10, np030 denotes [N/Fe]=+0.30, and om01 denotes [O/Fe]=-0.1

COMPOSITION/Age
Y Age 1 Gyr 5 Gyr 13.5 Gyr
0.24 1Gyr 5Gyr 13.5Gyr
0.32 1Gyr 5Gyr 13.5Gyr
0.33 1Gyr 5Gyr 13.5Gyr
0.34 1Gyr 5Gyr 13.5Gyr
0.36 1Gyr 5Gyr 13.5Gyr
0.38 1Gyr 5Gyr 13.5Gyr
0.40 1Gyr 5Gyr 13.5Gyr
0.44 1Gyr 5Gyr 13.5Gyr

ATLAS/SYNTHE

ATLAS/SYNTHE were used to create stellar atmosphere models for temperatures from 6000K down to ~3700K, at a selection of values for Log(g), and for a wavelength range of 250 - 2000 nm. The model grid is accessible from the table below. Files within the subdirectories are named giving the Teff and Log(g), following the format atlas_4000k_logg4.0.dat. The files are ascii format, with columns of Wavlength (nm) and Flux (erg/sec/cm2/Angstrom/Steradian). An introduction to running ATLAS/SYNTHE models can be found in pdf form here.

If you'd like to run your own ATLAS/SYNTHE models at any of the compositions listed in the table below, the ODF tables are available here.

These abundances are based on those measured for Omega Centauri by Marino et al. (2012). Follow the links in the table to find atmosphere models for the given [C,N,O/Fe] composition.

ATLAS9

COMPOSITION
[C/Fe] [N/Fe] +0.30 +0.90 +1.45
-0.65 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50
-0.20 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50
+0.20 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50

SYNTHE

COMPOSITION
[C/Fe] [N/Fe] +0.30 +0.90 +1.45
-0.65 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50
-0.20 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50
+0.20 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50 [O/Fe]=-0.10, +0.20, +0.50

PHOENIX

PHOENIX was used to create low temperature models, below the limits for ATLAS/SYNTHE. The grid is not as complete as the ATLAS/SYNTHE grid, but still covers a few different compositions. The model grid is accessible here. A big thank you to Peter Hauschildt and Derek Homeier for their help in running these models.