Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Near IR Spectroscopic monitoring of WR 140 during the 2001 periastron
  passage   We present new spectra of WR 140 (HD 193793) in the JHK bands with some
covering the 1.083-micron He I emission line at higher resolution, observed
between 2000 October and 2003 May to cover its 2001 periastron passage. The WC7
+ O4-5 spectroscopic binary WR 140 is the prototype of colliding-wind, episodic
dust-making Wolf-Rayet systems which also show strong variations in radio and
X-ray emission. The JHK spectra showed changes in continuum and in the
equivalent widths of the WC emission lines, consistent with formation of dust
starting between 2001 January 3 and March 26 (orbital phases 0.989 and 0.017)
and its subsequent fading and cooling. The 1.083-micron He I line has a P-Cygni
profile which showed variations in both absorption and emission components as
WR 140 went through periastron passage. The variation of the absorption
component yielded tight constraints on the geometry of the wind-collision
region, giving theta = 50 +/- 8 degrees for the opening semi-angle of the
interaction `cone', indicating a wind-momentum ratio of the O to the WR
star=0.1, about three times larger than previously believed. As the system
approached periastron, the emission component showed the appearance of a
significant sub-peak, movement of which across the profile was seen to be
consistent with its formation in wind material flowing along the contact
discontinuity between the two stellar winds and the changing orientation of the
colliding wind region. The flux carried in the sub-peak exceeded the X-ray
fluxes measured at previous periastron passages. This additional source of
radiative cooling of the shock-heated gas probably causes it to depart from
being adiabatic around periastron passage, thereby accounting for the departure
of the X-ray flux from its previously expected $1/d$-dependency.

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The categories of this paper are: cmp-lg
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The categories of this paper are: funct-an
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: nucl-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: q-bio
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat