Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: BZ Cam during its 1999/2000 optical low state   We report optical observations of the VY Scl star BZ Cam during its previous
optical low state in 1999/2000. We find drastic variations in the line
profiles. Narrow-band imaging observations show that its nebula extends farther
than previously known and seems to be composed of two components. We determine
the [OIII] line intensity of BZ Cam's nebula to 4.8 * 10^-13 erg/cm^2/s. We
discover a proper motion of BZ Cam of 25+-2 mas/yr which together with the
systemic radial velocity yields a space velocity of 125 km/s. We re-interpret
the nebula as being photo-ionized by hypothesized transient, luminous,
supersoft X-ray emission during optical low states, and shaped by the
transverse motion of BZ Cam.

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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
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The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int