Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray Spectroscopy of the Radiation-Driven Winds of Massive Stars: Line
  Profile and Line Ratio Diagnostics   Massive stars drive powerful, supersonic winds via the radiative momentum
associated with the thermal UV emission from their photospheres. Shock
phenomena are ubiquitous in these winds, heating them to millions, and
sometimes tens of millions, of degrees. The emission line spectra from the
shock-heated plasma provide powerful diagnostics of the winds' physical
conditions, which in turn provide constraints on models of wind shock heating.
Here I show how x-ray line transfer is affected by photoelectric absorption in
the partially ionized component of the wind and how it can be modeled to
determine the astrophysically important mass-loss rates of these stellar winds.
I also discuss how photoexcitation out of metastable excited levels of
helium-like ions can provide critical information about the location of the hot
plasma in magnetically channeled massive star winds.

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The categories of this paper are: cond-mat
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: stat
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: hep-lat
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The categories of this paper are: quant-ph
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The categories of this paper are: eess
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The categories of this paper are: hep-th
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The categories of this paper are: plasm-ph