Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: FUSE Snap-Shot Survey of O VI Variability in the Winds of 66 OB-Type
  Stars   We have used the Far Ultraviolet Spectroscopic Explorer (FUSE) to conduct a
snap-shot survey of O VI variability in the winds of 66 OB-type stars in the
Galaxy and the Magellanic Clouds. These time series consist of two or three
observations separated by intervals ranging from a few days to several months.
Although these time series provide the bare minimum of information required to
detect variations, this survey demonstrates that the O VI doublet in the winds
of OB-type stars is variable on various scales both in time and velocity. For
spectral types from O3 to B1, 64% vary in time. At spectral types later than
B1, no wind variability is observed. This fraction represents a lower limit on
the true incidence of variability in the O VI wind lines, which is very common
and probably ubiquitous. The observed variations extend over several hundreds
of km/s of the wind profile and can be strong. The width over which the wind O
VI profile varies is only weakly correlated with the terminal velocity (\vinf),
but a significant correlation (close to a 1:1 relationship) is derived between
the maximum velocity of the variation and \vinf. High velocity O VI wind
absorption features (possibly related to the discrete absorption components
seen in other wind lines) are also observed in 46% of the cases for spectral
types from O3 to B0.5. These features are variable, but the nature of their
propagation cannot be determined from this survey. If X-rays can produce
sufficient O VI by Auger ionization of O VI, and the X-rays originate from
strong shocks in the wind, this study suggests that stronger shocks occur more
frequently near \vinf, causing an enhancement of O VI near \vinf.

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The categories of this paper are: nlin
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org