Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Possibility of Emersion of the Outer Layers in a Massive Star
  Simultaneously with Iron-Core Collapse: A Hydrodynamic Model   We analyze the behavior of the outer envelope in a massive star during and
after the collapse of its iron core into a protoneutron star (PNS) in terms of
the equations of one-dimensional spherically symmetric ideal hydrodynamics. The
profiles obtained in the studies of the evolution of massive stars up to the
final stages of their existence, immediately before a supernova explosion
(Boyes et al. 1999), are used as the initial data for the distribution of
thermodynamic quantities in the envelope.We use a complex equation of state for
matter with allowances made for arbitrary electron degeneracy and relativity,
the appearance of electron-positron pairs, the presence of radiation, and the
possibility of iron nuclei dissociating into free nucleons and helium nuclei.
We performed calculations with the help of a numerical scheme based on
Godunov's method. These calculations allowed us to ascertain whether the
emersion of the outer envelope in a massive star is possible through the
following two mechanisms: first, the decrease in the gravitational mass of the
central PNS through neutrino-signal emission and, second, the effect of hot
nucleon bubbles, which are most likely formed in the PNS corona, on the
envelope emersion. We show that the second mechanism is highly efficient in the
range of acceptable masses of the nucleon bubbles ($\leq 0.01M_\odot$)
simulated in our hydrodynamic calculations in a rough, spherically symmetric
approximation.

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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
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The categories of this paper are: mtrl-th
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The categories of this paper are: stat
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The categories of this paper are: patt-sol
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The categories of this paper are: cs
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
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The categories of this paper are: physics
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The categories of this paper are: adap-org