The processes taking place on the surface of active stars are believed to be driven by the magnetic dynamo, which is also responsible for the formation of sunspots or solar flares. In our research group called STARK (Stellar Activity Research at Konkoly Observatory), we investigate processes related to magnetic phenomena observed on stars of different types, ages, and evolutionary stages. Among other things, we are looking for the answer to what the role of magnetic activity is in terms of stellar evolution, as well as the state of the circumstellar environment, and ultimately the emergence and development of life.
The webpage of the group can be found here.
STARK – Two important results:
1. Flare activity and inferences on habitability
Vida, K., Oláh, K., Kővári, Zs., et al.: Flaring Activity of Proxima Centauri from TESS Observations: Quasiperiodic Oscillations during Flare Decay and Inferences on the Habitability of Proxima b, The Astrophysical Journal, Volume 884, Issue 2, article id. 160, 9 pp. (2019). https://ui.adsabs.harvard.edu/abs/2019ApJ...884..160V/abstract
Flare activity and inferences on habitability
Proxima Centauri is the closest star to the Sun, and its Earth-like planet Proxima b may even be habitable. Previous numerical models did not rule out the presence of liquid water on the planet's surface. We investigated the flare activity of the star and concluded that frequent and energetic flares reduce the chances of habitability of Proxima Cen b.
kép: ProCen.webp, Credit: Ricardo Ramirez and James Jenkins (Department of Astronomy, Universidad de Chile)
2. Magnetic activity confined by tidal forces
Kővári, Zs., Kriskovics, L., Oláh, K., et al.: A confined dynamo: Magnetic activity of the K-dwarf component in the pre-cataclysmic binary system V471 Tauri, Astronomy & Astrophysics, Volume 650, id. A158 (2021)
https://ui.adsabs.harvard.edu/abs/2021A%26A...650A.158K/abstract
Magnetic activity can be strongly influenced by a nearby companion star. That's what's happening in V471 Tauri, a binary star formed by a magnetically active red dwarf star and a white dwarf companion, locked together in a tight orbit by gravity. We find a weak differential rotation in the spotted red dwarf component, which is most likely the result of the tidal confinement by the white dwarf. As further evidence of the strong interaction, we confirm the presence of a permanent dominant spot (active longitude) on the red dwarf facing the white dwarf.
kép: interacting-binaries.jpg Credit: phys.org