Thesis Topic: The mass-loss process in cool evolved stars
Thesis Supervisor: Markus Wittkowski
Abstract
Cool evolved stars on the horizontal branch, red giant branch, asymptotic giant branch, and red supergiants experience a strong mass loss, which is important both for the further evolution of these stars toward planetary nebulae or toward core-collapse supernovae, as well as for enriching the interstellar medium.
The physical processes that drive this mass-loss process are not well constrained for all cool evolved stars. They may include pulsation and convection, possibly temporally and spatially localised as seen during the recent great dimming event of Betelgeuse, or also chromospheric stellar activity or radiative pressure on molecular lines. Different processes may be dominant at different evolutionary stages and masses. Through spatially resolved observations using optical interferometry, we will empirically study the regions close to the stellar surface, where the mass-loss process is initiated.
Depending on the intest, the thesis can concentrate on red giants, AGB stars, or RSG stars. Interferometric data are already available, and further data can be obtained in the course of the thesis.
References
Climent, J. B. et al. 2020, A&A, 635, A160
González-Torà, G., et al. 2023, A&A, 669, 76
Kravchenko, K., et al. 2020, A&A, 642, A235
Wittkowski, M., et al. 2017, A&A, 606, L1
Wittkowski, M., et al. 2017, A&A, 601, A3
Wittkowski, M., et al. 2018, A&A, 613, L7
Talk at GAPS 2021 "unsolved problems in red giants and supergiants":
https://www.youtube.com/watch?v=W76rGhu9efk&list=PLxx4ZaPdBhzcoyvziF1jaybXujgIEbdrF&index=2