Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Pulsation of Chi Cygni Imaged by Optical Interferometry; a Novel
  Technique to Derive Distance and Mass of Mira Stars   We present infrared interferometric imaging of the S-type Mira star Chi
Cygni. The object was observed at four different epochs in 2005-2006 with the
IOTA optical interferometer (H band). Images show up to 40% variation in the
stellar diameter, as well as significant changes in the limb darkening and
stellar inhomogeneities. Model fitting gave precise time-dependent values of
the stellar diameter, and reveals presence and displacement of a warm molecular
layer. The star radius, corrected for limb darkening, has a mean value of 12.1
mas and shows a 5.1mas amplitude pulsation. Minimum diameter was observed at
phase 0.94+/-0.01. Maximum temperature was observed several days later at phase
1.02+/-0.02. We also show that combining the angular acceleration of the
molecular layer with CO (Delta v = 3) radial velocity measurements yields a
5.9+/-1.5 mas parallax. The constant acceleration of the CO molecules -- during
80% of the pulsation cycle -- lead us to argument for a free-falling layer. The
acceleration is compatible with a gravitational field produced by a
2.1(+1.5/-0.7) solar mass star. This last value is in agreement with
fundamental mode pulsator models. We foresee increased development of
techniques consisting in combining radial velocity with interferometric angular
measurements, ultimately allowing total mapping of the speed, density, and
position of the diverse species in pulsation driven atmospheres.

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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: math
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The categories of this paper are: adap-org
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The categories of this paper are: physics
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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: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: dg-ga
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The categories of this paper are: eess
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin