Infrared variability of the Seyfert galaxy NGC 3783

Abstract

The results of about 15 years of monitoring of the variable Seyfert 1 galaxy NGC 3783 in the infrared are presented. The spectrum of the variable component stays constant in shape. Changes in the infrared appear to lag those in the ultraviolet by about 80 to 90 d. Like the other Seyfert 1 galaxies Fairall 9 and NGC 1566, the near-infrared behaviour of NGC 3783 can be modelled by a dust shell at about 1500 K whose heating depends on changes in the UV flux of the central power source.