The effect of activity on the fundamental properties of low-mass stars
[eng] The comparison between stellar structure models and observations of low-mass stars revealed that the stellar radii predicted by models for these stars are about 10% lower than observed, while effective temperatures are about 5% higher. Eclipsing binary stars turned out to be a very useful tool...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2010 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/35275 |
| Acceso en línea: | https://hdl.handle.net/2445/35275 http://www.tdx.cat/TDX-0131111-125418 http://hdl.handle.net/10803/759 |
| Access Level: | acceso abierto |
| Palabra clave: | Estels binaris Evolució estel·lar Estructura estel·lar Double stars Stars - Evolution Stars-Structure |
| Sumario: | [eng] The comparison between stellar structure models and observations of low-mass stars revealed that the stellar radii predicted by models for these stars are about 10% lower than observed, while effective temperatures are about 5% higher. Eclipsing binary stars turned out to be a very useful tool to test stellar structure models because the masses and the radii of its components can be determined with very high accuracy. The analysis of the orbital velocity of each component, observed through the Doppler effect, and the luminosity variability due to eclipses, can lead to the fundamental properties of the stars with accuracies better than the 2% level. In this thesis, the fundamental properties of the binary systems CM Draconis and IM Virginis have been obtained. The comparison of these systems, as well as other systems with well-known fundamental properties, has been used to test the stellar structure models. The results indicate that the magnetic activity present on these binary stars may be the cause of the differences between models and observations. The magnetic activity has two effects on the stars, on the one hand, activity reduces the efficiency of the convective transport in the stellar interior, and on the other hand, activity may be associated with the appearance of spots on the photosphere of these stars. When both effects are taken into account, stellar structure models correctly reproduce the observations, thus solving the problem of the discrepancies between models and observations for low-mass stars. KEY WORDS: Low-mass stars, stellar structure, stellar evolution, stellar activity, eclipsing binary stars, spectroscopic binary stars |
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