Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Parent Stars of Extrasolar Planets VI: Abundance Analyses of 20 New
  Systems   The results of new spectroscopic analyses of 20 recently reported extrasolar
planet parent stars are presented. The companion of one of these stars, HD
10697, has recently been shown to have a mass in the brown dwarf regime; we
find [Fe/H] $= +0.16$ for it. For the remaining sample, we derive [Fe/H]
estimates ranging from -0.41 to $+0.37$, with an average value of $+0.18 \pm
0.19$. If we add the 13 stars included in the previous papers of this series
and 6 other stars with companions below the 11 M$_{\rm Jup}$ limit from the
recent studies of Santos et al., we derive $<$[Fe/H]$> = +0.17 \pm 0.20$.
  Among the youngest stars with planets with F or G0 spectral types, [Fe/H] is
systematically larger than young field stars of the same Galactocentric
distance by 0.15 to 0.20 dex. This confirms the recent finding of Laughlin that
the most massive stars with planets are systematically more metal rich than
field stars of the same mass. We interpret these trends as supporting a
scenario in which these stars accreted high-Z material after their convective
envelopes shrunk to near their present masses. Correcting these young star
metallicities by 0.15 dex still does not fully account for the difference in
mean metallicity between the field stars and the full parent stars sample.
  The stars with planets appear to have smaller [Na/Fe], [Mg/Fe], and [Al/Fe]
values than field dwarfs of the same [Fe/H]. They do not appear to have
significantly different values of [O/Fe], [Si/Fe], [Ca/Fe], or [Ti/Fe], though.

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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
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The categories of this paper are: cond-mat
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The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: econ
29
The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: nlin
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The categories of this paper are: stat