Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Evolution of C/O in Dwarf Galaxies from HST Fos Observations   We present FOS observations of O III] 1666 A and C III] 1909 A emission in H
II regions in dwarf irregular galaxies to measure C/O abundance ratios in those
galaxies. We observe a continuous increase in C/O with increasing O/H over the
range -4.7 < log(O/H) < -3.6. One interpretation is that the most metal-poor
galaxies are the youngest and dominated by the products of early enrichment by
massive stars, while more metal-rich galaxies show increasing, delayed
contributions of C from intermediate mass stars. However, recent evolution
models for massive stars including mass loss suggest that the yield of C
relative to O may increase with metallicity; new chemical evolution models for
the solar neighborhood which account for this predict a C/O abundance evolution
similar to that observed in the metal-poor galaxies. The C/N ratio increases
steadily with O/H in the irregular galaxies, but is much smaller in solar
neighborhood stars and H II regions. This may indicate that the bulk of N
production is decoupled from that of C in the Galaxy.

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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
19
The categories of this paper are: eess
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The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-th
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The categories of this paper are: q-bio