Discovery of a highly ionized, low mass-loss wind and a corona seen in absorption in the G9 II star HR 6902.

Abstract

IUE observations of HR 6902 (G9II + B9V) 1 and 2 days before and during total eclipse of the B star are discussed. The G bright giant has a highly ionized, hot (Te = 87,000 K) wind seen as C IV, Si IV, and C II resonance-line scattering of B-star photons during totality, with a mass-loss rate of 2 x 10 to the -11th solar mass/yr (+ or - factor 3). It is the first cool giant in which a hot wind has been detected. HR 6902 is also the first cool star in which a 'corona' is seen in absorption in C IV, Si IV, C II, and Fe III lines. In a line of sight corresponding to an effective height of 0.06 G-star radii, the Te is 58,000 K.