The Evolution of Rotation and Magnetic Activity in 94 Aqr Aa from Asteroseismology with TESS

Metcalfe, Travis S.; van Saders, Jennifer L.; Basu, Sarbani; Buzasi, Derek; Chaplin, William J.; Egeland, Ricky; Garcia, Rafael A.; Gaulme, Patrick; Huber, Daniel; Reinhold, Timo; Schunker, Hannah; Stassun, Keivan G.; Appourchaux, Thierry; Ball, Warrick H.; Bedding, Timothy R.; Deheuvels, Sébastien; González-Cuesta, Lucía; Handberg, Rasmus; Jiménez, Antonio; Kjeldsen, Hans; Li, Tanda; Lund, Mikkel N.; Mathur, Savita; Mosser, Benoit; Nielsen, Martin B.; Noll, Anthony; Çelik Orhan, Zeynep; Örtel, Sibel; Santos, Ângela R. G.; Yildiz, Mutlu; Baliunas, Sallie; Soon, Willie
Bibliographical reference

The Astrophysical Journal

Advertised on:
9
2020
Number of authors
32
IAC number of authors
3
Citations
24
Refereed citations
22
Description
Most previous efforts to calibrate how rotation and magnetic activity depend on stellar age and mass have relied on observations of clusters, where isochrones from stellar evolution models are used to determine the properties of the ensemble. Asteroseismology employs similar models to measure the properties of an individual star by matching its normal modes of oscillation, yielding the stellar age and mass with high precision. We use 27 days of photometry from the Transiting Exoplanet Survey Satellite to characterize solar-like oscillations in the G8 subgiant of the 94 Aqr triple system. The resulting stellar properties, when combined with a reanalysis of 35 yr of activity measurements from the Mount Wilson HK project, allow us to probe the evolution of rotation and magnetic activity in the system. The asteroseismic age of the subgiant agrees with a stellar isochrone fit, but the rotation period is much shorter than expected from standard models of angular momentum evolution. We conclude that weakened magnetic braking may be needed to reproduce the stellar properties, and that evolved subgiants in the hydrogen shell-burning phase can reinvigorate large-scale dynamo action and briefly sustain magnetic activity cycles before ascending the red giant branch.
Related projects
Helio and Asteroseismology
Helio and Astero-Seismology and Exoplanets Search
The principal objectives of this project are: 1) to study the structure and dynamics of the solar interior, 2) to extend this study to other stars, 3) to search for extrasolar planets using photometric methods (primarily by transits of their host stars) and their characterization (using radial velocity information) and 4) the study of the planetary
Savita
Mathur