Warm Disk Coronae in Classical T Tauri Stars

Abstract

It is proposed that a warm disk corona is a characteristic feature ofthe accretion process in a classical T Tauri star, based on analyses ofthe [O I] lambda lambda 6300, 5577 emission and the central absorptionsin the Balmer lines of hydrogen. Calculations are presented to determinethe physical conditions needed to produce the hydrogen and O Iexcitation. They indicate that a substantial fraction of the energyreleased in the accretion of matter through the disk may be dissipatedat the disk surface in order to heat the corona.