Magnetohydrodynamics of Accretion Disks

Abstract

Solar physics has close relationships to accretion disk physics. Galeev, Rosner & Vaiana (1979) proposed that accretion disks might have magnetically structured corona consisting of magnetic loops. Their model was based on Skylab soft X-ray observations of the solar corona. The soft X-ray telescope aboard the Yohkoh satellite revealed various dynamical activities in the solar corona which give clues to understanding the dynamics of accretion disk corona and X-ray time variabilities observed in black hole candidates (e.g., Miyamoto et al. 1994) and in star forming regions (e.g., Koyama et al. 1996). Recently, Ueno et al. (1997) showed that the power spectrum density of soft X-ray time variations of the solar corona have 1/f-like profiles similar to that of Cyg X-l. It is possible that the basic mechanism of X-ray fluctuations in accretion disks is similar to that of the solar corona.