Structure and evolution of stars deformed by a nearby companion
| Název práce v češtině: | Struktura a vývoj hvězd deformovaných gravitačním působením blízkého tělesa |
|---|---|
| Název v anglickém jazyce: | Structure and evolution of stars deformed by a nearby companion |
| Klíčová slova: | kontaktní dvojhvězdy|slapová deformace|hvězdná struktura |
| Klíčová slova anglicky: | contact binary stars|tidal deformation|stellar structure |
| Akademický rok vypsání: | 2020/2021 |
| Typ práce: | diplomová práce |
| Jazyk práce: | angličtina |
| Ústav: | Ústav teoretické fyziky (32-UTF) |
| Vedoucí / školitel: | doc. Mgr. Ondřej Pejcha, Ph.D. |
| Řešitel: | skrytý - zadáno a potvrzeno stud. odd. |
| Datum přihlášení: | 05.03.2021 |
| Datum zadání: | 20.04.2021 |
| Datum potvrzení stud. oddělením: | 25.05.2021 |
| Datum a čas obhajoby: | 03.02.2023 09:00 |
| Datum odevzdání elektronické podoby: | 05.01.2023 |
| Datum odevzdání tištěné podoby: | 05.01.2023 |
| Datum proběhlé obhajoby: | 03.02.2023 |
| Oponenti: | prof. Mgr. Jiří Krtička, Ph.D. |
| Zásady pro vypracování |
| The shape of equipotential surfaces in single stars in hydrostatic equilibrium depends on their rotation rate: non-rotating stars are spherically symmetric while rotating stars are axi-symmetric with respect to the axis of rotation. Presence of a nearby binary companion breaks this symmetry and the stellar shape resembles the so called Roche potential. In the extreme case of a contact binary, the two stars share a common envelope. The structure and energy transport inside contact binaries has been an unresolved problem since 1960s. Recent observations (Jayasinghe et al. 2020) provide a new interesting clue to this open problem: dichotomy at an effective temperature, where the mode of energy transport near the surface changes from radiative to convective (somewhat similar to the difference between diffusion and boiling of water). So far, the theoretical description of contact binaries were based on the assumption of two independent stars touching each other. The goal of this project is to theoretically develop an opposite extreme, where one star completely envelops its companion.
The work will include developing a method to calculate properties of highly non-spherical equipotentials (surface area, volume, mean surface gravity etc.) and implementing these results in a state-of-the-art evolution code MESA while learning about stellar evolution, convection and turbulence, radiation transport, microphysics of stellar interiors, and numerical solution of boundary value problems. The thesis might also explore the generation of magnetic fields in the envelopes of binary stars with possible applications to contact binaries and early stages of common envelope evolution. |
| Seznam odborné literatury |
| Jayasinghe, T., Stanek, K. Z., Kochanek, C. S., et al. 2020, MNRAS, 493, 4045, "The ASAS-SN catalogue of variable stars - VII. Contact binaries are different above and below the Kraft break", https://ui.adsabs.harvard.edu/abs/2020MNRAS.493.4045J/abstract
Paxton, B., Bildsten, L., Dotter, A., et al. 2011, ApJS, 192, 3, "Modules for Experiments in Stellar Astrophysics (MESA)", https://ui.adsabs.harvard.edu/abs/2011ApJS..192....3P/abstract Shu, F. H., Lubow, S. H., & Anderson, L. 1976, ApJ, 209, 536, "On the structure of contact binaries. I. The contact discontinuity.", https://ui.adsabs.harvard.edu/abs/1976ApJ...209..536S/abstract Endal, A. S. & Sofia, S. 1976, ApJ, 210, 184, "The evolution of rotating stars. I. Method and exploratory calculations for a 7 M sun star.", https://ui.adsabs.harvard.edu/abs/1976ApJ...210..184E/abstract |