Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical Spectroscopy Of The X-Ray Transient XTE J1118+480 In Outburst   We report on optical spectroscopic observations of the X-ray Transient XTE
J1118+480 covering the period from April 7, 2000 to July 4, 2000. The spectrum
is characterized by weak, broad, double-peaked Balmer and He lines on top of a
blue continuum of slope p ~ 1/3, as expected for an optically-thick accretion
disk. The weak Bowen blend seen in our spectra may indicate a low intrinsic
metallicity for the source. The presence of a partial S-wave pattern in the
HeII lambda-4686 line appears consistent with the reported photometric orbital
period Porb = 4.1 hr for XTE J1118+480. By using a combination of Doppler
mapping and various theoretical arguments, we constrain plausible orbital
parameters for the system: a mass ratio 0.02 <~ q <~ 0.1, an inclination i >~
70 deg for a neutron star primary, or 30 deg <~ i <~ 50 deg for a black hole
primary with a mass between 4 and 10 Msun. CaII absorption features observed at
very high resolution constrain the interstellar hydrogen absorption column
log[N_HI (cm^{-2})] ~ 20.45 +/- 0.2 and the identification of three absorbing
clouds indicate a distance to the source <~ 1 kpc, assuming the line-of-sight
to XTE J1118+480 has average high-latitude properties. These results are
discussed in the context of previous multiwavelength observations of this
unusual system.

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The categories of this paper are: math-ph
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The categories of this paper are: funct-an
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con
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The categories of this paper are: comp-gas
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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: q-bio