Abundances - for X-ray opacities - summary
July 28, 2010
D. Cohen

Abundances (and even moreso, overall metallicity) are the biggest uncertainty in modeling the wind opacity in the x-ray regime.  Ionization balance makes a small difference, but quite small (He-recombination in the outer wind aside - and so we generally use a "standard O star" mix of ionization stages). 

The big issues, then, for making an appropriate model of the X-ray opacity for a given star are: 

1. Which solar abundances? and
2. Are specific elements (esp. CNO) altered from their solar values? 

Note that for normal O stars in the Galaxy, there's little evidence for deviations from overall solar metallicity (though specific CNO abundances generally don't sum to the solar value - though the solar value is generally within the systematic uncertainties on these determinations). 

log 12 (H) scale:

        AGS05   Aspl09
He      10.93   10.98
C        8.39    8.47
N        7.78    7.87
O        8.66    8.73
Ne       7.84    7.97
Mg       7.53    7.64
Si       7.51    7.55
Fe       7.45    7.54


From Taresch et al. for HD 93129A (assuming their values are scaled to GS89 and then rescaling them to Aspl09):

Y_C = 0.25
Y_N = 3.02
Y_O = 0.47

Note that the sum of C, N, and O totals to 0.68 of Aspl09 solar

These are the values used for Maurice's opacity model (July 2010): kappa.HD93129A.CNOsubsolar.fits

12 Aug 2010:

And we have a "HD93129A.CNOsolar" version too, in which we scale up the C, N, and O abundances by 1/0.68 so that their sum is solar, giving individual abundances of: 

Y_C = 0.37
Y_N = 4.44
Y_O = 0.69



---- List of opacity files available for use with windtabs or for analyzing taustar --> Mdot ---

kappa_ags_zp_alt1 = CNO processed, solar (AGS05) metallicity; CNO rescaled back up to solar (in sum)
kappa_aspl09 = Asplund 09 solar abund w/ standard ion mix
kappa_solarAGS05 =  Asplund Gr. Sau. 05 solar abunda w/ different(?) ion mix
kappa.HD93129A.CNOsubsolar.dat = asp09 metallicity, w/ CNO altered acc. to Taresch; standard ion mix
kappa.HD93129A.CNOsolar.dat = asp09 metallicity, w/ CNO altered acc. to Taresch, but then rescaled so sum of C, N, and O = solar.  (T.'s determination gives 0.68 solar)