Andreas Sander - Deciphering the properties and impact of hot and massive stars

Speaker : Dr. Andreas Sander (Astronomisches Rechen-Institut, Heidelberg)
Date : May 7th, 2024
Title : Deciphering the properties and impact of hot and massive stars with detailed stellar atmosphere modelling
Abstract: Massive stars are astrophysical keystones, shaping our cosmic
history. As the progenitors of neutron stars and black holes,
massive stars reach all nuclear burning stages and - before
eventually collapsing - greatly enrich their surrounding medium
with momentum, matter, and ionizing radiation. This feedback of
massive stars is a building block for the evolution of galaxies,
initiating and inhibiting further star formation. In the
"afterlives" of massive stars, black holes and neutron stars can
merge with each other, giving rise a to Gravitational Wave events.
Yet, the overall picture of massive stars we draw in textbooks is
rather sketchy and new observational frontiers such as the strong
metal-enrichment in high-redshift galaxies discovered by JWST or
the black hole statistics obtained from Gravitational Waves only
add further pieces to the engmatic massive star puzzle.

For a better understanding of massive stars, it is essential to
properly determine their parameters and feedback. For young and
hot massive stars, many properties are only accessible via
spectroscopy. Their quantitative measurements and predictions
rely on suitable models for stellar atmospheres, which requires
sophisticated simulations to account for their non-equilibrium
conditions and strong stellar winds. In this talk, I will
introduce the techniques and challenges of atmosphere modelling
for hot, massive stars and their winds. Afterwards, I will present
a selection of the research efforts within my group demonstrating
the range of empirical and theoretical applications of modern
non-LTE stellar atmosphere models, such as the analysis of
important landmarks of massive star evolution, the search for
"hidden" post-interaction binaries, or theoretical insights on
radiation-driven winds.