X-ray temperatures and their radial distributions from winds of O-type supergiants: the effects of clumps
Abstract
Context. Based on the multiphase hydrodynamical flows and the clump model, a two-fluid model of the O stars ζ Ori A and ζ Pup is investigated, in which the flow is described by a set of two components.
Aims: I investigate the influence of clumps on the production of X-ray and derive wind parameters from a comparison with the X-ray temperature distributions in the wind of O-type supergiants.
Methods: The velocity structure of the clump is assumed to be beta law, thus the transonic velocity structure of the ambient wind can be attained via the shooting method.
Results: The mass, filling factor, and velocity structure of the clump are very sensitive to the post-shock temperatures. I find that the filling factor must be about 0.01 for fitting the observed X-ray temperatures. The mass of the clump cannot be smaller than 1018 g. A clump carries about 10-4 dot{M} and 10-5 dot{M} for ζ Ori A and ζ Pup, respectively. The model with the exponent of clump velocity β = 0.5-0.6 for O-type supergiants fits the observations better than one with the exponent β = 0.8.
Conclusions: These results indicate that the forward shock scenario can explain the X-ray emission, except for the hottest X-ray lines for O-type supergiants. Theoretical and observable evidence shows that a low velocity law should be applied to O-type supergiants.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 2010
- DOI:
- 10.1051/0004-6361/200912872
- Bibcode:
- 2010A&A...512A..50G
- Keywords:
-
- stars: early type;
- stars: individual: ζ Ori A;
- stars: individual: ζ Pup;
- stars: winds;
- outflows;
- X-ray: stars