Nitrogen in the Early Universe Original Research Article

The most important contributor to the nitrogen production in the Universe is predicted to be intermediate mass (IM) asymptotic giant branch (AGB) stars. We test this prediction through observations of the C and N abundances on the surfaces of metal-poor stars that are believed to have accreted material from a (now gone) AGB companion. The [C/N] measurement from our sample and from the literature show [C/N] ratios that are too high to come from IMS AGB stars that have undergone hot bottom burning. We discuss possible solutions to the problem.