Mass loss of rotating stars at very low metallicity

Abstract

Some indirect observations, as the high fraction of Be stars at low metallicity, or the necessity for massive stars to be important sources of primary nitrogen, seem to indicate that very metal poor stars were fast rotators. As a consequence of this fast rotation, these stars, contrarily to current wisdom, might lose large amounts of mass during their lifetime. In this paper, we review various mechanisms triggered by rotation which may induce strong mass loss at very low metallicity. The most efficient process comes from surface enrichments in CNO elements which then drive mass loss by stellar winds. Due to this process, a fast rotating 60 M${}_{\odot }$ with metallicities in the range of $Z=10^{-8}$ and $10^{-5}$, can lose between 30 and 55% of its initial mass. This rotationally wind ejected material participates to the chemical evolution of the interstellar medium, enriching it exclusively in H- and He-burning products. In particular, metal poor fast rotating stars may play a key role for explaining the origin of the peculiar abundance pattern observed at the surface of the extremely metal-poor C-rich stars, for explaining the chemical inhomogeneities observed in globular clusters, and the presence of stars in $\omega$ Cen with a very high helium content .

15 pages, 3 figures, contribution to Nuclei in the Cosmos IX, Proceedings of Science, accepted

References in corpus (10)

• The Progenitor Stars of Gamma-Ray Bursts
• Fast rotating massive stars and the origin of the abundance patterns in galactic globular clusters
• Evolution of rapidly rotating metal-poor massive stars towards gamma-ray bursts
• Stellar evolution with rotation XII: Pre-supernova models
• On the self-enrichment scenario of galactic globular clusters: Constraints on the IMF
• A strong case for fast stellar rotation at very low metallicities
• Fundamental Properties of O-Type Stars
• On the Origin of the High Helium Sequence in $\omega$ Centauri
• New Nitrogen and Carbon in AF-supergiants
• Single massive stars at the critical rotational velocity: possible links with Be and B[e] stars