Simulations of the small scale surface dynamo of cool main sequence stars
Additional information
Authors
Riva F.,
Canivete Cuissa J. R.,
Steiner O.
Type
Article in conference proceedings
Year
2022
Language
English
Abstract
A widely accepted explanation for the origin of the ubiquitous small-scale magnetic field observed on the solar surface is thepresence of a small-scale dynamo (SSD) operating in the sub-surface layers of the Sun. To shed light on the functioning ofthis SSD, a number of numerical studies of a realistic solaratmosphere have been carried out in the past two decades,greatly improving our knowledge on how an SSD operates.Nevertheless, virtually no studies focused on SSD action on thesurface of other main-sequence stars. This motivates the workreported here. Hydro and magneto-hydrodynamics simulations of asmall partial volume encompassing the surface layers of F5V,G2V, K2V, and K8V main-sequence stars are carried out with theradiative magnetohydrodynamic CO5BOLD code, investigating howSSD action can amplify a tiny seed magnetic field. Inparticular, the growth rate of the magnetic to kinetic energyratio is characterized in terms of the Reynolds and magneticReynolds numbers of the simulations, and of the effectivetemperature and surface gravity of each star. It is found thatthe small-scale dynamo operating in the K2V simulation is thefastest in amplifying the magnetic energy among the four casesconsidered here. However, similar saturation values of themagnetic to kinetic energy ratio, of about 1%, are found at thesurface for all the four stars. Ultimately, we investigate thespatial structure of the magnetic field resulting from SSDaction and how it interacts with the plasma in the stellaratmospheres.
Conference proceedings
Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun
Series
Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun
Start page number
125-
