Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Massive Star Populations in Wolf-Rayet Galaxies   We analyze longslit spectral observations of fourteen Wolf-Rayet galaxies
from the sample of Schaerer, Contini & Pindao (1999). All 14 galaxies show
broad Wolf-Rayet emission in the blue region of the spectrum, consisting of a
blend of NIII4640, CIII4650, CIV4658, and HeII4686 emission lines, which is a
spectral characteristic of WN stars. Broad CIV5808 emission, termed the red
bump, is detected in 9 galaxies and CIII5996 is detected in 6 galaxies. These
emission features are due to WC stars. We derive the numbers of late WN and
early WC stars from the luminosity of the blue and red bumps, respectively. The
number of O stars is estimated from the luminosity of the Hbeta emission line,
after subtracting the contribution of WR stars. The Schaerer & Vacca 1998
(hereafter SV98) models predict that the number of WR stars relative to O
stars, N_WR/N_O, increases with metallicity. For low metallicity galaxies, the
results agree with predictions of evolutionary synthesis models for galaxies
with a burst of star formation, and indicates an IMF slope -2 < Gamma < -2.35
in the low metallicity regime. For high metallicity galaxies our observations
suggest a Salpeter IMF (Gamma = -2.35) and an extended short burst. The main
possible sources of error are the adopted luminosities for single WCE and WNL
stars. We also report, for the first time, NGC 450 as a galaxy with WR
characteristics.

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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: supr-con
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-th
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: eess
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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: physics
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The categories of this paper are: nucl-th