Quantitative analysis of resolved X-ray emission line profiles of O stars

David H. Cohen (1), Maurice A. Leutenegger (2), Richard H. D. Townsend (3)

1 - Swarthmore College
2 - Columbia, GSFC
3 - Delaware

By quantitatively fitting simple emission line profile models that include both atomic opacity and porosity to the Chandra X-ray spectrum of $zeta$ Pup, we are able to explore the trade-offs between reduced mass-loss rates and wind porosity. We find that reducing the mass-loss rate of $zeta$ Pup by roughly a factor of four, to 1.5 times 10^{-6} M_sun/yr, enables simple non-porous wind models to provide good fits to the data. If, on the other hand, we take the literature mass-loss rate of 6 times 10^{-6} M_sun/yr, then to produce X-ray line profiles that fit the data, extreme porosity lengths -- of $h_{infty} approx 3$ Rstar -- are required. Moreover, these porous models do not provide better fits to the data than the non-porous low optical depth models. Additionally, such huge porosity lengths do not seem realistic in light of 2-D numerical simulations of the wind instability.

Reference: Appearing in "Clumping in Hot Star Winds," eds. Hamann, Feldmeier, & Oskinova, Potsdam: Univ.-Verl., 2007
Status: Conference proceedings

Weblink: http://astro.swarthmore.edu/~cohen/Papers/cohen_potsdam.pdf


Email: cohen@astro.swarthmore.edu