Carbon Abundances in Starburst Galaxies of the Local Universe
  The cosmological origin of carbon, the fourth most abundant element in the
Universe, is not well known and matter of heavy debate. We investigate the
behavior of C/O to O/H in order to constrain the production mechanism of
carbon. We measured emission-line intensities in a spectral range from 1600 to
10000 \AA\ on Space Telescope Imaging Spectrograph (STIS) long-slit spectra of
18 starburst galaxies in the local Universe. We determined chemical abundances
through traditional nebular analysis and we used a Markov Chain Monte Carlo
(MCMC) method to determine where our carbon and oxygen abundances lie in the
parameter space. We conclude that our C and O abundance measurements are
sensible. We analyzed the behavior of our sample in the [C/O] vs. [O/H] diagram
with respect to other objects such as DLAs, neutral ISM measurements, and disk
and halo stars, finding that each type of object seems to be located in a
specific region of the diagram. Our sample shows a steeper C/O vs. O/H slope
with respect to other samples, suggesting that massive stars contribute more to
the production of C than N at higher metallicities, only for objects where
massive stars are numerous; otherwise intermediate-mass stars dominate the C
and N production.
