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 10 18 g. A clump carries about 10 −4Ṁ and 10 −5Ṁ 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.

Coronal winds powered by radiative driving

“…For more recent treatments and applications, see Howk et al (2000) and Guo (2010). The equation of motion obeyed by the blobs is…”

X-ray diagnostics of massive star winds

“…Another family of models suggests that radiatively driven blobs of matter plough through an ambient gas that is less radiatively accelerated (Lucy, 2012;Guo, 2010). These blobs might be the result of an instability (Lucy and White, 1980), or seeded at or below the stellar photosphere (Waldron and Cassinelli, 2009;Cantiello and Braithwaite, 2011).…”