Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Subluminous O stars from the ESO Supernova Progenitor Survey -
  Observation versus Theory   The ESO Supernova Progenitor Survey (SPY) has identified 58 (mostly
helium-rich) subluminous O stars. We use the Balmer line strength to
distinguish sdO from He-sdO (no Balmer lines) and present the results of the
analyses of high resolution optical VLT-UVES spectra using an extensive grid of
NLTE atmosphere models covering a large range in Teff, log g and helium
abundances. The stellar atmospheric parameters are derived from line profile
fits using a chi**2 technique. The resulting distribution in the (Teff, log g)
diagram as well as the luminosity function are discussed in the context of
stellar evolution scenarios. By combining our results with those for the sdB
stars from SPY (Lisker et al. 2004) we discuss the implications for binary
population synthesis models of Han et al. (2003). Models with a low CEE
efficiency and a constant mass ratio distribution provide a reasonable
explanation of the observed properties of the SPY sample of sdB and sdO stars
indicating that the sdO stars form the hot and luminous extension of the sdB
sequence. However, for the He-sdO stars none of the considered evolution
scenarios are in agreement with the measured parameters of our programme stars.
We conclude that He-sdO stars are formed by a different process than the sdB
and sdO stars.

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The categories of this paper are: acc-phys
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The categories of this paper are: econ
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
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The categories of this paper are: physics
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The categories of this paper are: math
10
The categories of this paper are: q-bio
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The categories of this paper are: nlin