Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The origin and evolution of r- and s-process elements in the Milky Way
  stellar disk   Knowledge of abundance ratios as functions of metallicity can lead to
insights on the origin and evolution of our Galaxy and its stellar populations.
We aim to trace the chemical evolution of the neutron-capture elements Sr, Zr,
La, Ce, Nd, Sm, and Eu in the Milky Way stellar disk to constrain the formation
sites of these elements as well as to probe the evolution of the Galactic thin
and thick disks. Using spectra of high resolution and high signal-to-noise we
determine Sr, Zr, La, Ce, Nd, Sm, and Eu abundances for a sample of 593 F and G
dwarf stars in the Solar neighbourhood. We present abundance results for Sr,
Zr, La, Ce, Nd, Sm and Eu. We find that Nd, Sm, and Eu show trends similar to
what is observed for the alpha-elements when compared to [Fe/H]. [Sr/Fe] and
[Zr/Fe] show decreasing abundance ratios for increasing metallicity, reaching
sub-solar values at super-solar metallicities. [La/Fe] and [Ce/Fe] do not show
any clear trend with metallicity. The rapid neutron-capture process is active
early in the Galaxy, mainly in type II supernovae from stars in the mass range
8-10 M_sun. Eu is almost completely produced by r-process but Nd and Sm show
similar trends to Eu even if their s-process component is higher. Sr and Zr
show significant enrichment at low metallicity that requires extra r-process
production, that probably is different from the classical r-process. Finally,
La and Ce are mainly produced via s-process from AGB stars in mass range 2-4
M_sun. The trend of [X/Fe] with age found could be explained by considering
that the decrease in [X/Fe] for the thick disk stars can be due to the decrease
of type II supernovae with time meaning a reduced enrichment of r-process
elements in the interstellar medium. In the thin disk the trends are flatter
that probably is due to that the main production from s-process is balanced by
Fe production from type Ia supernovae.

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The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
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The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat