Weak- and strong-field dynamos: from the Earth to the stars

J. Morin , E. Dormy (1) , M. Schrinner (1) , J. -F. Donati (2)

1 IPGP - Institut de Physique du Globe de Paris
2 IRAP - Institut de recherche en astrophysique et planétologie

Observations of magnetism in very low mass stars recently made important progress, revealing characteristics that are now to be understood in the framework of dynamo theory. In parallel, there is growing evidence that dynamo processes in these stars share many similarities with planetary dynamos. We investigate the extent to which the weak-field versus strong-field bistability predicted for the geodynamo can apply to recent observations of two groups of very low mass fully-convective stars sharing similar stellar parameters but generating radically different types of magnetic fields. Our analysis is based on previously published spectropolarimetric and spectroscopic data. We argue that these can be interpreted in the framework of weak- and strong-field dynamos.

Keywords: dynamo; planets and satellites: magnetic fields; stars: low-mass; stars: magnetic field; dynamo

Domains: Sciences of the Universe [physics]

J. Morin, E. Dormy, M. Schrinner, J. -F. Donati. Weak- and strong-field dynamos: from the Earth to the stars. Monthly Notices of the Royal Astronomical Society: Letters, 2011, 418, pp.L133-L137. ⟨10.1111/j.1745-3933.2011.01159.x⟩. ⟨insu-03606429⟩