Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A strong neutron burst in jet-like supernovae of spinstars   Some metal-poor stars have abundance patterns which are midway between the
slow (s) and rapid (r) neutron capture processes. We show that the helium shell
of a fast rotating massive star experiencing a jet-like explosion undergoes two
efficient neutron capture processes: one during stellar evolution and one
during the explosion. It eventually provides a material whose chemical
composition is midway between the s- and r-process. A low metallicity
40~$M_{\odot}$ model with an initial rotational velocity of $\sim
700$~km~s$^{-1}$ was computed from birth to pre-supernova with a nuclear
network following the slow neutron capture process. A 2D hydrodynamic
relativistic code was used to model a $E = 10^{52}$~erg relativistic jet-like
explosion hitting the stellar mantle. The jet-induced nucleosynthesis was
calculated in post-processing with a network of 1812 nuclei. During the star's
life, heavy elements from $30 \lesssim Z \lesssim 82$ are produced thanks to an
efficient s-process, which is boosted by rotation. At the end of evolution, the
helium shell is largely enriched in trans-iron elements and in (unburnt)
$^{22}$Ne, whose abundance is $\sim 20$ times higher than in a non-rotating
model. During the explosion, the jet heats the helium shell up to $\sim 1.5$
GK. It efficiently activates ($\alpha,n$) reactions, such as
$^{22}$Ne($\alpha,n$), and leads to a strong n-process with neutron densities
of $\sim 10^{19} - 10^{20}$~cm$^{-3}$ during $0.1$~second. This has the effect
of shifting the s-process pattern towards heavier elements (e.g. Eu). The
resulting chemical pattern is consistent with the abundances of the
carbon-enhanced metal-poor r/s star CS29528-028, provided the ejecta of the jet
model is not homogeneously mixed. This is a new astrophysical site which can
explain at least some of the metal-poor stars showing abundance patterns midway
between the s- and r-process.

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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-th
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph
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The categories of this paper are: funct-an