Balmer profile variations during the fading of the Seyfert 1 galaxy Fairall 9

Abstract

The authors present variations of the Hβ profile during the fading of the Seyfert 1 nucleus of Fairall 9, between 1981 and 1984. Decays with time scales from 250 days to 1000 days are found for the ultraviolet and optical continua, as well as for the Hβ line emission. These cannot be easily interpreted in terms of a change in the accretion rate in a steady state thick disk, while disk instabilities provide time scales of the right order of magnitude.