Research Division Seminar
Stellar abundance determinations in hot massive stars -- Why is this (still) problematic?

Abstract

Massive stars are real cosmic engines, and they have a large impact onto our Universe from early times on. Unfortunately, their evolution is still uncertain in many aspects, even on the main sequence. To check and improve corresponding predictions (needed, e.g., in galaxy simulations as sub-grid physics), various efficiency factors for internal processes such as core-envelope mixing need to be calibrated, by means of observational constraints. To this end, the measurement of chemical abundances, in particular for C,N,O, is a primary tool. Compared to low and intermediate mass stars and also to massive Red Supergiants, these measurements (by means of quantitative spectroscopy) are much more complex, since particularly deviations from LTE and the presence of inhomogeneous winds affect the observed line-strengths, and lead to significant uncertainties in the derived abundance values. In this talk, I will discuss these problems at hand of specific examples, summarize important results of the current state of the art, and provide a quick outlook what's next to come (within a collaboration with IAC-members).

Zoom link: https://rediris.zoom.us/j/98925990368?pwd=LJDIa3HSX4zIHM74vimXTwiabfrreN.1