Prominence activity on the rapidly rotating field star HD 197890

摘要: Time-resolved Hα spectra are presented of the recently discovered, rapidly rotating young field star HD 197890. The observations contain rapid absorption and emission transients that cross rotationally broadened profile from blue to red on time-scales order 1 h. behaviour is consistent with models proposed for another star, AB Dor, in which cool clouds material trapped corotating closed magnetic structures above surface scatter chromospheric photons out line sight. Measurements radial acceleration these indicate they positioned at about or outside Keplerian corotation radius