Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Time-resolved ultraviolet spectroscopy of the compact interacting binary
  QU Car   We present HST/STIS (1160--1700A) echelle spectra of the cataclysmic variable
(CV) star, QU Car, observed in time-tag mode at three epochs. In catalogues
this binary is classified as a nova-like variable. We find evidence of a
high-state non-magnetic CV at low inclination, with unusually high ionisation.
We observed narrow absorption lines (few hundred km/s wide) in N V1240, O V1371
and Si IV1398, as well as broader (HWZI ~1000km/s) emission in C III1176, C
IV1549 and He II1640, all with a superposed absorption component. High
ionisation is indicated by the unusually string He II emission and the relative
strength of the O V absorption line. The dereddened UV SED of, on average, -2.3
suggests that disc accretion dominates the spectral energy distribution. In two
observations velocity shifting is noted in the absorption lines on a timescale
long enough not to repeat within the ~2600-sec exposures. The absorption
superposed on the C IV emission line moves coherently with the N V and Si IV
absorption, suggesting the same origin for all absorption lines -- most likely
to be in the accretion disc atmosphere. Weak blueshifted absorption in NV and
C\IV provides evidence of an outflow component and we estimate a maximum
outflow velocity of ~2000km/s. This may be linked to a wind launched from
further out in the disc than is typically seen in those high-state non-magnetic
CV whose wind speeds are observed to reach to >4000km/s. Unusually, three
ionisation stages of carbon -- C II, C III and C IV -- are present in emission,
with line width increasing with higher ionisation. The presence of C II in
emission and the positive line-width/ionisation correlation is most easily
reconciled with an origin in a disc chromosphere, beyond the influence of the
EUV-emitting inner disc.

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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: cmp-lg
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
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The categories of this paper are: q-alg
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The categories of this paper are: math-ph
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The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: cs
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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: hep-ph
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The categories of this paper are: econ
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The categories of this paper are: cond-mat
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The categories of this paper are: ao-sci