Identifying red giant progenitors of hot subdwarfs in wide binaries
Fecha
2024
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Universidad de Valparaíso
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item.page.issne
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Facultad
Facultad de Ciencias
Departamento o Escuela
Instituto de Física y Astronomía
Determinador
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Especie
Nota general
Magíster de Astrofísica. Universidad de Valparaíso. 2024.
Resumen
Modern statistical analyses reveal that up to one-third of observable stars are in bi- nary systems, characterized by two stars orbiting each other. A thorough study of these binaries is essential for understanding the physics of binary interactions. Extensive inves- tigations have associated them with crucial universal phenomena, such as the formation of type Ia supernovae, blue stragglers, hot subdwarfs, cataclysmic variable stars, etc.
Furthermore, binaries offer the unique opportunity to measure stellar masses with high precision, without relying on complex physical models of stellar evolution. Instead, we can apply Kepler’s third law, a well-established principle. Thus, we employ these systems to calibrate measurements of stellar masses and mass-luminosity relations, a crucial component of the extragalactic cosmic ladder.
In addition to the fundamental applications mentioned above, binary systems serve as one of the most critical probes of stellar physics. This importance arises from the fact that a companion star can significantly alter the well-established evolutionary track of a single star, thereby prompting us to comprehend new physical phenomena associated with these systems.
This is the case for hot subdwarf B stars (sdBs) which are the naked helium cores of evolved stars, surrounded by a very thin hydrogen envelope, which puzzles researchers, as “canonical” stellar evolution scenarios cannot explain how the star lost almost all of its envelope.
Many evolutionary scenarios to explain the formation of these stars have been pro- posed over the years, while simultaneously, more and more observational evidence has been gathered. Today we believe that sdBs are solely formed by binary interactions, a topic that will be described in detail in the text.
Observationally, there are more sdB binaries in close systems (orbital periods of a few hours to a few days) compared to wide systems (orbital periods of 400 to 1600 days) because monitoring them with large programs is easier. However, in recent decades, a monitoring program of wide sdB binaries has been initiated. This thesis aims to complement this effort by focusing on the monitoring of progenitors of wide sdB binaries.
The main goal of this thesis is to identify all possible progenitors of sdBs in a volume- limited sample of stars up to 500 pc, which have been monitored by high-resolution spectroscopy, and determine their physical characteristics, such as surface temperature, surface gravity, mass, radius, etc.
Having a sample of progenitors of sdBs in wide binaries will help us to test the predicted correlations between sdB stars and their progenitors, and directly improve the theoretical models that predict the evolution of these fascinating objects.
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Valparaíso
Auspiciador
Palabras clave
Estrellas, Binarias eclipsantes