Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray Emission Line Profile Modeling of O stars: Fitting a
  Spherically-Symmetric Analytic Wind-Shock Model to the Chandra Spectrum of
  zeta Puppis   X-ray emission line profiles provide the most direct insight into the
dynamics and spatial distribution of the hot, X-ray-emitting plasma above the
surfaces of OB stars. The O supergiant zeta Puppis shows broad, blueshifted,
and asymmetric line profiles, generally consistent with the wind-shock picture.
We model the profiles of eight lines in the Chandra HETGS spectrum of this
prototypical hot star. The fitted lines indicate that the plasma is distributed
throughout the wind starting close to the photosphere, that there is
significantly less attenuation of the X-rays by the overlying wind than is
generally supposed, and that there is not a strong trend in wind absorption
with wavelength.

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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: gr-qc
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The categories of this paper are: eess