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On the Cosmic Origins of Carbon and Nitrogen
The behaviour of C/O and N/O ratios as a function of metallicity in HII regions in galaxies is characterised, and used to derive rough values of chemical yields from analytic models. These ‘analytic
Sulfur, Chlorine, and Argon Abundances in Planetary Nebulae. IV. Synthesis and the Sulfur Anomaly
We have compiled a large sample of O, Ne, S, Cl, and Ar abundances that have been determined for 85 Galactic planetary nebulae in a consistent and homogeneous manner using spectra extending from 3600
ABUNDANCES OF GALACTIC ANTICENTER PLANETARY NEBULAE AND THE OXYGEN ABUNDANCE GRADIENT IN THE GALACTIC DISK
We have obtained spectrophotometric observations of 41 anticenter planetary nebulae (PNe) located in the disk of the Milky Way. Electron temperatures and densities, as well as chemical abundances for
The UCSD HIRES/KECK I Damped Lya Abundance Database: IV. Probing Galactic Enrichment Histories with Nitrogen
We present 14 N^0 measurements from our HIRES/Keck database of damped Lya abundances. These data are combined with measurements from the recent and past literature to build an homogeneous, uniform
Carbon and Oxygen Abundances in Low Metallicity Dwarf Galaxies
The study of carbon and oxygen abundances yields information on the time evolution and nucleosynthetic origins of these elements, yet remains relatively unexplored. At low metallicities (12+log(O/H)
CNO Abundances in Metal-Rich Environments: Infrared Space Observatory Spectroscopy of Ionized Gas in M51
We present Infrared Space Observatory (ISO) Long Wavelength Spectrograph observations centered on the H II region CCM 10 in the spiral galaxy M51. We detect several emission lines in this spectrum,
On the Determination of N and O Abundances in Low Metallicity Systems
We show that in order to minimize the uncertainties in the N and O abundances of low-mass, low-metallicity (O/H ≤ 1/5 solar) emission-line galaxies, it is necessary to employ separate
A New Look at Carbon Abundances in Planetary Nebulae. IV. Implications for Stellar Nucleosynthesis
This paper is the fourth and final report on a project designed to study carbon abundances in a sample of planetary nebulae representing a broad range in progenitor mass and metallicity. We present
The Chemical Evolution of Carbon, Nitrogen, and Oxygen in Metal-poor Dwarf Galaxies
Ultraviolet nebular emission lines are important for understanding the time evolution and nucleosynthetic origins of their associated elements, but the underlying trends of their relative abundances
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