Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On Luminous Blue Variables as the Progenitors of Core-Collapse
  Supernovae, especially Type IIn Supernovae   Luminous blue variable (LBV) stars are very massive, luminous, unstable stars
that suffer frequent eruptions. In the last few years, these stars have been
proposed as the direct progenitors of some core-collapse supernovae (SNe),
particularly Type IIn SNe, in conflict with stellar evolution theory. In this
paper we investigate various scenarios wherein LBV stars have been suggested as
the immediate progenitors of SNe. Many of these suggestions stem from the fact
that the SNe appear to be expanding in a high density medium, which has been
interpreted as resulting from a wind with a high mass-loss rate. Others arise
due to perceived similarities between the SN characteristics and those of LBVs.
Only in the case of SN 2005gl do we find a valid possibility for an LBV-like
progenitor. Other scenarios encounter various levels of difficulty. The
evidence that points to LBVs as direct core-collapse SNe progenitors is far
from convincing. High mass-loss rates are often deduced by making assumptions
regarding the wind parameters, which are contradicted by the results
themselves. A high density need not necessarily imply a high wind mass-loss
rate: wind shocks sweeping up the surrounding medium may give a high density
shell with a low associated wind mass-loss rate. High densities may also arise
due to wind clumps, or due to a previous LBV phase before the SN explodes as a
Wolf-Rayet star. Some Type IIn SNe appear to signify more a phase in the life
of a SN than a class of SNe, and may arise from more than one type of
progenitor. A Wolf-Rayet phase that lasts for a few thousand years or less
could be one of the more probable progenitors of Type IIns, and channels for
creating short-lived W-R phases are briefly discussed.

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The categories of this paper are: eess
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: cs
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The categories of this paper are: nlin
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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: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ph
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The categories of this paper are: math