Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Carbon Shell or Core Ignitions in White Dwarfs Accreting from Helium
  Stars   White dwarfs accreting from helium stars can stably burn at the accreted rate
and avoid the challenge of mass loss associated with unstable Helium burning
that is a concern for many Type Ia supernovae scenarios. We study binaries with
helium stars of mass $1.25 M_\odot\le M_{\rm{He}} \le 1.8 M_\odot$, which have
lost their hydrogen rich envelopes in an earlier common envelope event and now
orbit with periods ($P_{\rm orb}$) of several hours with non-rotating $0.84$
and $1.0 M_\odot$ C/O WDs. The helium stars fill their Roche lobes (RLs) after
exhaustion of central helium and donate helium on their thermal timescales
(${\sim}10^5$yr). As shown by others, these mass transfer rates coincide with
the steady helium burning range for WDs, and grow the WD core up to near the
Chandrasekhar mass ($M_{\rm Ch}$) and a core carbon ignition. We show here,
however, that many of these scenarios lead to an ignition of hot carbon ashes
near the outer edge of the WD and an inward going carbon flame that does not
cause an explosive outcome. For $P_{\rm orb} = 3$ hours, $1.0 M_\odot$ C/O WDs
with donor masses $M_{\rm He}\gtrsim1.8 M_\odot$ experience a shell carbon
ignition, while $M_{\rm He}\lesssim1.3 M_\odot$ will fall below the steady
helium burning range and undergo helium flashes before reaching core C
ignition. Those with $1.3 M_\odot \lesssim M_{\rm He} \lesssim 1.7 M_\odot$
will experience a core C ignition. We also calculate the retention fraction of
accreted helium when the accretion rate leads to recurrent weak helium flashes.

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The categories of this paper are: math
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: ao-sci
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The categories of this paper are: cond-mat
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The categories of this paper are: cs
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: plasm-ph
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The categories of this paper are: physics
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The categories of this paper are: gr-qc
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The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph