Vliv rekombinace vodíku a hélia na splynutí hvězd
| Thesis title in Czech: | Vliv rekombinace vodíku a hélia na splynutí hvězd |
|---|---|
| Thesis title in English: | The effect of hydrogen and helium recombination on stellar mergers |
| Academic year of topic announcement: | 2024/2025 |
| Thesis type: | Bachelor's thesis |
| Thesis language: | |
| Department: | Institute of Theoretical Physics (32-UTF) |
| Supervisor: | doc. Mgr. Ondřej Pejcha, Ph.D. |
| Author: |
| Guidelines |
| Many interesting astrophysical systems of binary stars, including sources of gravitational waves (binary neutron stars and black holes), evolve through a rapid phase, where one of the stars spirals in through the envelope of the other one - the common envelope evolution. During this event, the binary loses substantial amounts of mass, angular momentum, and energy. The associated shrinking of the orbit facilitates the subsequent merger due to the emission of gravitational waves.
There is evidence that the unbinding of gas is greatly helped by the "heat" released during the recombination of hydrogen and helium in an expanding envelope. Multidimensional simulations typically include this effect using a "realistic" equation of state, which neglects radiation transport effects. 1D models include prescriptions for radiative and convective energy transport, but these are rooted in hydrostatic stellar models and become problematic in an expanding medium. None of the existing models takes into account the possibility of non-equilibrium between radiation and gas. The goals of this thesis are: - review the microphysics of hydrogen and helium recombination and the associated production of photons - review advanced models of radiation transport, which allow non-equilibrium between gas and radiation and are valid in optically-thick and optically-thin regimes - review advanced models of convection and turbulence - figure out a way how to combine these elements in the context of common envelope evolution - develop a dynamical 1D model, which numerically illustrates these pieces of physics - using the model, asses the importance of recombination for common envelope evolution and observed astrophysical systems |
| References |
| https://ui.adsabs.harvard.edu/abs/2018MNRAS.478.1818G/abstract
https://ui.adsabs.harvard.edu/abs/2023LRCA....9....2R/abstract https://ui.adsabs.harvard.edu/abs/2018ApJ...863L..14S/abstract https://ui.adsabs.harvard.edu/abs/2018ApJ...858L..24I/abstract https://ui.adsabs.harvard.edu/abs/2019MNRAS.487.5304M/abstract https://ui.adsabs.harvard.edu/abs/1998A%26A...340..419W/abstract https://ui.adsabs.harvard.edu/abs/2007ApJ...667..626K/abstract https://ui.adsabs.harvard.edu/abs/2005A%26A...441..271U/abstract |
| Preliminary scope of work |
| http://utf.mff.cuni.cz/~pejcha/ |