Element Abundances at High Redshifts: The N/O Ratio at Low Metallicity
Our knowledge of galactic chemical evolution is currently limited to observations of Milky Way stars and H II regions of nearby galaxies. Damped Lyman~$α$ systems offer a new approach for tracking the evolution of normal galaxies from early epochs to the present day. Here we report the first measurements of nitrogen abundances in galaxies with less than 1/100 of solar metallicity, a range unexplored by previous observations.
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