Stellar winds of boring stars...

Séminaire IPAG de Aline Vidotto (U. of St Andrews) , jeudi 21 juin 2012 à 11h00, IPAG seminar room

The stellar winds of cool, main-sequence (boring) stars are very tenuous and persist during the star lifetime. Although they may not cause a fundamental impact in the evolutionary track of a star (opposed to winds of massive stars), they regulate the rotation of the star and can affect surrounding planets. Because these winds are incredibly tenuous, up to now, there have not been any direct measurements of their properties (except for the Sun itself). To determine the fundamental properties of such winds (mass-loss rates, terminal velocities), one has to rely on very few indirect methods that probe the wind of these objects. On the theoretical front, (magnetohydrodynamics) numerical simulations can definitely help ascertain the aspects of the wind. Aiming at characterising more realistically such winds, we have been implementing in our numerical simulations observationally-derived surface magnetic field maps, which show the diverse magnetic field strengths and topologies that these stars host. Ultimately, understanding these types of stellar winds leads to a characterisation of the environment surrounding exoplanets. Although these environments may be potentially dangerous for a planet’s atmosphere, the interaction between planets and the host star coronal winds can provide other avenues for planet detection and maybe even assess planetary properties (eg, planet’s magnetic field), which would otherwise remain unknown. In this talk I will overview some of our recent works on simulations of (entertaining) winds of cool, main-sequence (boring) stars and their impact on surrounding planets. In particular, I will present results for two specific planet-hosting stars : Tau Boo and WASP-12.