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| Paper: |
Moffat Clumps as the Source of X-Rays from Single WR Stars |
| Volume: |
465, Four Decades of Massive Star Research - A Scientific Meeting in Honor of Anthony J. Moffat |
| Page: |
140 |
| Authors: |
Gayley, K. G. |
| Abstract: |
Embedded shocks in hot-star winds
can produce X-rays either when low-density gas receives significant extra acceleration and rams the slower
wind above, or when high-density
gas significantly lags the ambient windspeed and is rammed from below.
Here I explore the latter possibility by considering
the ramifications of a subpopulation of Moffat clumps that are
hypothesized to be significantly slower
than the ambient wind, even at large radii.
It is found that the requirement to have such clumps is that they be “sluggish and sticky”, meaning that they
are not radiatively driven, and they accrete most of the material that impinges upon them.
The combination allows the clumps to form in the wind in a dynamically self-consistent
way, and if they begin forming deep enough in the wind, they can remain significantly slow for many flow times.
Such clumps are generally not seen in hydrodynamic simulations, so may require special
seeding deep in the wind.
All the same, they would need to be quite rare given the X-ray energetics,
so they would only need to be the “tail of the distribution” of the observed Moffat clumps.
Thus they might not appear in simulations not designed to generate them, or missed in simulations
that are not expressly looking for them. |
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