Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: FUV Spectroscopy of the Supersoft X-ray Binary RX J0513.9-6951   We have obtained spectroscopy with the Far Ultraviolet Spectroscopic Explorer
(FUSE) of the supersoft X-ray binary RX J0513.9-6951 over a complete binary
orbital cycle. The spectra show a hot continuum with extremely broad O VI
emission and weak Lyman absorptions. He II emission is weak and narrow, while N
III and C III emissions are undetected, although lines from these ions are
prominent at optical wavelengths. The broad O VI emission and Lyman absorption
show radial velocity curves that are approximately antiphased and have
semiamplitudes of ~117 +- 40 and 54 +- 10 km/s, respectively. Narrow emissions
from He II and O VI show small velocity variations with phasing different from
the broad O VI, but consistent with the optical line peaks. We also measure
considerable changes in the FUV continuum and O VI emission line flux. We
discuss the possible causes of the measured variations and a tentative binary
interpretation.

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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg
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The categories of this paper are: alg-geom
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The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: hep-ex
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The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: acc-phys