TY  - CHAP
A1  - Leutenegger, M. A.
A1  - Cohen, David H.
A1  - Kahn, S. M.
A1  - Owocki, S. P.
A1  - Paerels, F. B. S.
T1  - Resonance scattering in the X-ray emission lines profiles of ζ Puppis
N2  - We present XMM-Newton Reflection Grating Spectrometer observations of pairs of X-ray emission line profiles from the O star ζ Pup that originate from the same He-like ion. The two profiles in each pair have different shapes and cannot both be consistently fit by models assuming the same wind parameters. We show that the differences in profile shape can be accounted for in a model including the effects of resonance scattering, which affects the resonance line in the pair but not the intercombination line. This implies that resonance scattering is also important in single resonance lines, where its effect is difficult to distinguish from a low effective continuum optical depth in the wind. Thus, resonance scattering may help reconcile X-ray line profile shapes with literature mass-loss rates.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18085
ER  - 
TY  - CHAP
A1  - Cohen, David H.
A1  - Leutenegger, M. A.
A1  - Townsend, R. H. D.
T1  - Quantitative analysis of resolved X-ray emission line profiles of O stars
N2  - By quantitatively fitting simple emission line profile models that include both atomic opacity and porosity to the Chandra X-ray spectrum of ζ 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 ζ Pup by roughly a factor of four, to 1.5 × 10−6 M⊙ yr−1, 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 6×10−6 M⊙ yr−1, then to produce X-ray line profiles that fit the data, extreme porosity lengths – of h∞ ≈ 3 R∗ – 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.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18115
ER  -