Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Progenitor Masses of Wolf-Rayet Stars and Luminous Blue Variables
  Determined from Cluster Turn-offs. I. Results from 19 OB Associations in the
  Magellanic Clouds   We combine new CCD UBV photometry and spectroscopy with that from the
literature to investigate 19 Magellanic Cloud OB associations that contain
Wolf-Rayet (WR) and other types of evolved massive stars. Our spectroscopy
reveals a wealth of newly identified interesting objects, including early
O-type supergiants, a high mass double-lined binary in the SMC, and, in the
LMC, a newly confirmed LBV (R 85), a newly discovered WR star (Sk-69 194), and
a newly found luminous B[e] star (LH85-10). We use the data to evaluate the
extent that each association is coeval, and for the ones with little age
spread, determine the turn-off masses of the unevolved stars, as a means of
finding the progenitor masses of LBVs and WRs. Our data is also used to find
the (minimum) bolometric corrections that apply to these evolved objects. We
find that WRs in the SMC come from only the highest mass stars (>70Mo), while
in the LMC the WNEs come from a wide range of masses---possibly all stars with
masses >30Mo pass though a WNE stage at LMC metallicities. In both the SMC and
LMC the WCs appear to come from the same mass range as do the WNs, a finding
that has important implications for interpreting the WC/WN ratio among Local
Group galaxies. LBVs appear to come from the very highest mass stars. The
Ofpe/WN9 stars, sometimes implicated in the "LBV phenonomon" come from very
modest mass stars, 25-35Mo, suggesting a different origin for their
variability. The BCs of WRs are considerably more negative than those of O-type
stars, with BC(WNE)=-6.0 mag and BC(WC4)=-5.5mag; more modest values are found
for the Ofpe/WN9 stars (-2 to -4 mag). These findings are consistent with
recent analysis done with Hillier's "standard model".

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The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: ao-sci
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The categories of this paper are: supr-con
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio
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The categories of this paper are: physics
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an