The Puzzling Frequencies of CEMP and NEMP Stars

Abstract

We present the results of binary population simulations of carbon- and nitrogen-enhanced metal-poor (CEMP and NEMP) stars. We show that the observed paucity of very nitrogen-rich stars puts strong constraints on possible modifications of the initial mass function at low metallicity.Comment: 3 pages, contribution to "The Origin of the Elements Heavier than Iron" in honor of the 70th birthday of Roberto Gallino, Torino, Italy, September 200