Research Division Seminar
Understanding the properties and impact of hot, massive stars with detailed stellar atmosphere modelling

Resumen

Albeit rare in absolute numbers, massive stars are shaping our cosmic history as they are connected to many astrophysical key processes. Commonly defined as stars with an initial mass of more than 8 times the mass of our Sun, massive stars are the progenitors of black holes and neutron stars, reaching all nuclear burning stages before eventually undergoing their inevitable core collapse. In their comparably short life, these luminous objects have an enormous impact on their galactic environment, enriching the surrounding medium with momentum, matter, and ionizing radiation. This so-called "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, overall textbook picture typically drawn of massive stars is rather sketchy and often also at odds with observational constraints. New 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 enigmatic 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. Finally, I will give an outlook on current observational challenges and theoretical insights from 2D and 3D simulations raising a new need to reconsider some of the current paradigms in massive star atmosphere modelling.