Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectroscopic Identification of Faint White Dwarf Candidates in the
  Praesepe Open Star Cluster   We present spectroscopic observations of the remaining four candidate white
dwarfs in Praesepe. All four candidates are quasars with redshifts between 0.8
and 2.8. One quasar, LB 6072, is observed to have a strong metal-line
absorption system blueward of the quasar redshift. The lack of additional white
dwarfs in Praesepe leaves the total known white-dwarf population of the cluster
at five, well below the number expected from commonly-assumed initial mass
functions, though several undiscovered cluster WDs may lie in the outer regions
of the cluster. All known Praesepe member white dwarfs are concentrated within
0.6 deg of the cluster center, and the radial profile of cluster white dwarfs
is quite similar to the profile of massive cluster stars. This profile is
mildly inconsistent with that of ~1Mo cluster stars and suggests that the white
dwarfs did not receive a velocity kick during the progenitor star's mass loss
phases. If complete, the observed Praesepe white dwarf population is consistent
with a steeper high-end initial-mass function than commonly assumed, though the
calculated slopes are inconsistent with the present-day mass function of
Praesepe. Searches for white dwarfs outside the core of Praesepe and further
study of the white dwarf populations of additional open clusters is necessary
to constrain further the underlying cause of the white dwarf deficit.

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The categories of this paper are: patt-sol
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The categories of this paper are: stat
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The categories of this paper are: acc-phys
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The categories of this paper are: nlin
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The categories of this paper are: q-alg
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The categories of this paper are: q-bio
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The categories of this paper are: chao-dyn
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-lat
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The categories of this paper are: chem-ph
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-th