Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Breaking news from the HST: The central star of the Stingray Nebula is
  now returning towards the AGB   SAO244567 is a rare example of a star that allows us to witness stellar
evolution in real time. Between 1971 and 1990 it changed from a B-type star
into the hot central star of the Stingray Nebula. This observed rapid heating
has been a mystery for decades, since it is in strong contradiction with the
low mass of the star and canonical post-asymptotic giant branch (AGB)
evolution. We speculated that SAO244567 might have suffered from a late thermal
pulse (LTP) and obtained new observations with HST/COS to follow the evolution
of the surface properties of SAO244567 and to verify the LTP hypothesis. Our
non-LTE spectral analysis reveals that the star cooled significantly since 2002
and that its envelope is now expanding. Therefore, we conclude that SAO244567
is currently on its way back towards the AGB, which strongly supports the LTP
hypothesis. A comparison with state-of-the-art LTP evolutionary calculations
shows that these models cannot fully reproduce the evolution of all surface
parameters simultaneously, pointing out possible shortcomings of stellar
evolution models. Thereby, SAO244567 keeps on challenging stellar evolution
theory and we highly encourage further investigations.

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The categories of this paper are: funct-an
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The categories of this paper are: hep-ph
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The categories of this paper are: econ
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The categories of this paper are: cs
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The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: chem-ph
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The categories of this paper are: eess
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The categories of this paper are: supr-con
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The categories of this paper are: math
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The categories of this paper are: nlin
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The categories of this paper are: q-bio
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph