Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-velocity white dwarfs: thick disk, not dark matter   We present an alternative interpretation of the nature of the extremely cool,
high-velocity white dwarfs identified by Oppenheimer et al (2001) in a
high-latitude astrometric survey. We argue that the velocity distribution of
the majority of the sample is more consistent with the high-velocity tail of a
rotating population, probably the thick disk, rather than a pressure-supported
halo system. Indeed, the observed numbers are well matched by predictions based
on the kinematics of a complete sample of nearby M dwarfs. Analysing only stars
showing retrograde motion gives a local density close to that expected for
white dwarfs in the stellar (R^-3.5) halo. Under our interpretation, none of
the white dwarfs need be assigned to the dark-matter, heavy halo. However,
luminosity functions derived from observations of these stars can set important
constraints on the age of the oldest stars in the Galactic Disk.

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The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph