Coronae of Young Fast Rotators

’Slow’ and Fast Rotators Among Hypervelocity Stars

We measure the rotational velocities of the late B-type hypervelocity stars HVS7 and HVS8 from high resolution spectroscopy to be 60 ± 17 km s and 260 ± 70 km s. The ’slow’ rotation of HVS7 is consistent with an origin in a binary system, however, the fast rotation of HVS8 is more common of single B-type stars. Our results suggest that HVS8 could have been ejected by a mechanism other than that...

M-dwarf Fast Rotators and the Detection of Relatively Young Multiple M-star Systems

We have searched the Kepler light curves of ∼ 3900 M-star targets for evidence of periodicities that indicate, by means of the effects of starspots, rapid stellar rotation. Several analysis techniques, including Fourier transforms, inspection of folded light curves, ‘sonograms’, and phase tracking of individual modulation cycles, were applied in order to distinguish the periodicities due to rap...

Acceleration and collimation of relativistic plasmas ejected by fast rotators

A stationary self-consistent outflow of a magnetised relativistic plasma from a rotating object with an initially monopole-like magnetic field is investigated in the ideal MHD approximation under the condition σ/U 0 > 1, where σ is the ratio of the Poynting flux over the mass energy flux at the equator and the surface of the star, with U0 = γ0v0/c and γ0 the initial four-velocity and Lorentz fa...

Physics of Stellar Coronae

Massive Coronae of Galaxies

There is reason to suspect that about half of the baryons are in pressure-supported plasma in the halos of normal galaxies, drawn in by gravity along with about half of the dark matter. To be consistent with the observations this baryonic component, the corona, would have to be hotter than the kinetic temperature of the dark matter in the halo so as to produce acceptable central electron densit...