Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: GCIRS 7, a pulsating M1 supergiant at the Galactic centre. Physical
  properties and age   The stellar population in the central parsec of the Galaxy is dominated by an
old (several Gyr) population, but young, massive stars dominate the luminosity
function. We have studied the most luminous of these stars, GCIRS 7, in order
to constrain the age of the recent star formation event in the Galactic Centre
and to characterise it as an interferometric reference for observations of the
Galactic Centre with the instrument GRAVITY, which will equip the Very Large
Telescope Interferometer in the near future. We present the first H-band
interferometric observations of GCIRS 7, obtained using the PIONIER visitor
instrument on the VLTI using the four 8.2-m unit telescopes. In addition, we
present unpublished K-band VLTI/AMBER data, build JHKL light-curves based on
data spanning 4 decades, and measured the star's effective temperature using
SINFONI spectroscopy. GCIRS 7 is marginally resolved at H-band (in 2013:
uniform-disk diameter=1.076+/-0.093mas, R=960+/-92Rsun at 8.33+/-0.35kpc). We
detect a significant circumstellar contribution at K-band. The star and its
environment are variable in brightness and in size. The photospheric H-band
variations are well modelled with two periods: P0~470+/-10 days (amplitude
~0.64mag) and long secondary period LSP~2700-2850 days (~1.1mag). As measured
from CO equivalent width, <Teff>=3600+/-195K. The size, periods, luminosity
(<Mbol>=-8.44+/-0.22) and effective temperature are consistent with an M1
supergiant with an initial mass of 22.5+/-2.5Msun and an age of 6.5-10Myr
(depending on rotation). This age is in remarkable agreement with most
estimates for the recent star formation event in the central parsec. Caution
should be taken when using this star as an interferometric reference as it is
variable in size, is surrounded by a variable circumstellar environment and
large convection cells may form on its photosphere.

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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: cs
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The categories of this paper are: adap-org
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-fin
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The categories of this paper are: cond-mat
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The categories of this paper are: nucl-th
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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: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: math