External Colloquium | Gerald Handler (Nicolaus Copernicus Astronomical Center)

Pulsations and close binary stars: new synergies

Astrophysics depends on the knowledge of stellar parameters, structure and evolution; the more accurate the more insightful. The most accurate stellar parameters over a wide range of evolutionary stages are determined via the analysis of (detached) eclipsing binary systems, whereas stellar interior structure can be inferred from investigations of stellar oscillations - asteroseismology. However, there are some ambiguities in these methods that can be resolved applying both methods, to pulsating stars in binary systems. On the other hand, proximity effects can complicate such analysis - or be an asset. An example are the so-called tidally tilted pulsators, stars in close binary systems that have their pulsational axes tilted into the orbital plane by the gravitational pull of their companion. Such objects were serendipitously discovered in space photometric data from NASA's TESS mission. One of their assets is that one sees the pulsations over all aspect angles during an orbital cycle. This permits their association with the surface distortions they create, leading to pulsational mode identification, and thus overcomes of the most important obstacles for asteroseismology. Another useful feature of these objects is that the orbital and pulsational geometries depend on each other and can therefore be determined in two ways. Recently it has been realized that some of these objects pulsate around three different axes. A theory has been developed to explain the physical origin of triaxial pulsations and that predicts how these can be identified, and the first observational proofs have been obtained. Triaxial pulsators hold the promise to sound stellar interiors in 3D. In this presentation, this very new field of research will be reviewed and it is attempted to convey a good perception of the geometries involved.

• Datum:
  13. März 2025, 14:00 – 16:00
  
  
• Ort:

  Maria Margaretha Kirch Haus Conference Room

  
  
• Kontakt:
  Julián Alvarado-Gómez