Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relationship between the Elemental Abundances and the Kinematics of
  Galactic-Field RR Lyrae Stars   Data of our compiled catalog containing the positions, velocities, and
metallicities of 415 RR~Lyrae variable stars and the relative abundances
[el/Fe] of 12~elements for 101 RR~Lyrae stars, including four $\alpha$~elements
(Mg, Ca, Si, and Ti), are used to study the relationships between the chemical
and spatial--kinematic properties of these stars. In general, the dependences
of the relative abundances of $\alpha$~elements on metallicity and velocity for
the RR~Lyrae stars are approximately the same as those for field dwarfs.
Despite the usual claim that these stars are old, among them are
representatives of the thin disk, which is the youngest subsystem of the
Galaxy. Attention is called to the problem of low-metallicity RR~Lyrae stars.
Most RR~Lyrae stars that have the kinematic properties of thick disk stars have
metallicities ${\rm [Fe/H]} < -1.0$ and high ratios [$\alpha$/Fe]$ \approx
0.4$, whereas only about 10\,\% of field dwarfs belonging to the so-called
"low-metallicity tail" have this chemical composition. At the same time, there
is a sharp change in [$\alpha$/Fe] in RR~Lyrae stars belonging just to the
thick disk, providing evidence for a long period of formation of this
subsystem. The chemical compositions of SDSS J1707+58, V455 Oph, MACHO
176.18833.411, V456 Ser, and BPS CS 30339--046 do not correspond to their
kinematics. While the first three of these stars belong to the halo, according
to their kinematics, the last two belong to the thick disk. It is proposed that
they are all most likely extragalactic, but the possible appearance of some of
them in the solar neighborhood as a result of the gravitational action of the
bar on field stars cannot be ruled out.

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The categories of this paper are: supr-con
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The categories of this paper are: hep-lat
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The categories of this paper are: q-alg
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: cond-mat
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The categories of this paper are: math-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-th