Abstract

Contributed Talk - Splinter Stellar

Friday, 25 September 2020, 15:35   (virtual room M)

Stellar mergers as the origin of magnetic massive stars

F.R.N. Schneider, S.T. Ohlmann, Ph. Podsiadlowski, F. Roepke, S.A. Balbus, R. Pakmor, V. Springel
University of Heidelberg, HITS, Max Planck Society (MPCDF & MPA Garching), University of Oxford

The first magnetic field in a star other than the Sun was detected in 1947 in the star 78 Vir. Today, we know that about 10% of these intermediate-mass and high-mass stars have strong, large-scale surface magnetic fields whose origin has remained a major mystery till today. It has been suggested that merging of main-sequence and pre-main-sequence stars could produce such strong fields. The massive star Tau Sco is a prominent member of the group of magnetic stars and appears to be surprisingly young compared to other presumably coeval members of the Upper Scorpius association. In this talk, I will present 3D magneto-hydrodynamical simulations of the coalescence of two massive main-sequence stars and 1D stellar evolution computations of the subsequent evolution of the merger product that can explain Tau Sco's magnetic field, apparent youth and other observed characteristics. I will argue that field amplification in stellar mergers is a general mechanism to form strongly-magnetised massive stars. Such stars are promising progenitors of magnetars, which may give rise to some of the enigmatic fast radio bursts, and their supernova explosions may be affected by the strong magnetic fields.