Three-dimensional radiation hydrodynamics of red supergiant envelopes

Ma, Jingze (2026): Three-dimensional radiation hydrodynamics of red supergiant envelopes. Dissertation, LMU München: Faculty of Physics

Abstract

Massive stars are the progenitors of supernovae and gravitational wave sources. However, we still do not understand how to map the massive star types to the transients they produce, or how to map massive star evolution to the gravitational wave signatures we observe. This confusion is in part because our theoretical understanding of massive stars is mostly based on one-dimensional (1D) spherically-symmetric stellar models. However, as suggested by observations and analytical arguments, evolved massive stars should deviate significantly from spherical symmetry. The multidimensional physics of massive stars can only be captured by three-dimensional (3D) simulations, but so far there have been very few simulations studying the 3D envelopes of massive stars. In this thesis, I describe a new computational tool to simulate 3D full-sphere massive star envelopes with accurate multi-scale radiation hydrodynamics. In the first part, I report a new angle-dependent radiation transport scheme I implemented in the 3D moving-mesh magnetohydrodynamic code AREPO. This technical advancement makes it possible for me to build the first models of 3D full-sphere red supergiant envelopes probing different evolutionary stages. In the second part, I show that convection in red supergiant envelopes is driven by plumes cooled from above, fundamentally different from what 1D theories describe. I argue that this cooling-driven convection leaves unique granulation signatures on the stellar surface and can be probed with interferometry, as demonstrated in the third part of this thesis. The fourth part shows 3D simulations of the final hundred years of red supergiant stars before their deaths, where increased luminosity triggers large-amplitude pulsations and creates a quasi-stationary cocoon around the star. I argue that this cocoon is the origin of circumstellar material observed in a high fraction of supernovae. In the fifth part, I continue investigating mass ejections from massive stars, in binary systems, with a 1D stellar evolution code. As envisioned in the last part of this thesis, all of these results pave the way for the initiation of the AREPO-Star project, aiming at building 3D simulations of massive star envelopes, binary interactions, and transients across the Hertzsprung-Russell diagram.

• Item Type: Theses (Dissertation, LMU Munich)
• Subjects: 500 Natural sciences and mathematics; 500 Natural sciences and mathematics > 530 Physics
• Faculties: Faculty of Physics
• Language: English
• Date of oral examination: 6. July 2026
• 1. Referee: Mink, Selma de
• Signature of the printed copy: 0001/UMC 32108