Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galactic Cepheids with Spitzer: II. Search for Extended Infrared
  Emission   A deep and detailed examination of 29 classical Cepheids with the Spitzer
Space Telescope has revealed three stars with strong nearby extended emission
detected in multiple bands which appears to be physically associated with the
stars. RS Pup was already known to possess extended infrared emission, while
the extended emission around the other two stars S Mus and delta Cep is newly
discovered in our observations. Four other stars GH Lup, l Car, T Mon and X Cyg
show tentative evidence for extended infrared emission. An unusual elongated
extended object next to SZ Tau appears to be a background or foreground object
in a chance alignment with the Cepheid. The inferred mass loss rates upper
limits for S Mus and delta Cep are in the range from 1e-9 to 1e-8 Msun/yr, with
the upper limit for RS Pup as high as 1e-6 Msun/yr. Mass loss during
post-main-sequence evolution has been proposed as a resolution to the
discrepancy between pulsational and dynamical masses of Cepheid variable stars:
dust in the lost material would make itself known by the presence of an
infrared bright nebula, or unresolved infrared excess. The observed frequency
of infrared circumstellar emission (<24%) and the mass loss rate we estimate
for our sources shows that dusty mass loss can only account for part of the
Cepheid mass loss discrepancy. Nevertheless, our direct evidence that mass loss
is active during the Cepheid phase is an important confirmation that these
processes need to be included in evolutionary and pulsation models of these
stars, and should be taken into account in the calibration of the Cepheid
distance scale.

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The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: nlin
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: nucl-th
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The categories of this paper are: patt-sol
3
The categories of this paper are: physics