Impact of rotational mixing on the global and asteroseismic properties of red giants

Abstract

The influence of rotational mixing on the global parameters and asteroseismic properties of red giant stars is reviewed. While red giants are generally characterised by low surface rotational velocities, they may have been rotating much more rapidly during the main sequence, so that the rotational history of a star has a large impact on its properties during the red giant phase. For stars massive enough to ignite helium burning in non-degenerate conditions, rotational mixing leads to a significant increase of the stellar luminosity and shifts the location of the core helium burning phase to a higher luminosity in the HR diagram. This results in a change of the seismic properties of red giants and of the fundamental parameters of a red giant star as determined by performing an asteroseismic calibration. For red giants with a lower mass that undergo the helium flash, rotational mixing decreases the luminosity of the bump at solar metallicity changing thereby the global and asteroseismic properties of these stars.

Proc. of the workshop "Red Giants as Probes of the Structure and Evolution of the Milky Way" (Roma, 15-17 Nov 2010), Astrophysics and Space Science Proceedings, ISBN 978-3-642-18417-8 (eds. A. Miglio, J. Montalban, A. Noels). Part of RedGiantsMilkyWay/2011/ proceedings available at http://arxiv.org/html/1108.4406v1