Abstract

Thermal emission from "planetary" discs is known in other stars such as β Pictoris. The emission, discovered by the IRAS satellite, is comparable in strength to that from the star itself at 60 µm wavelength, indicating a large quantity of material at radius ~ 100 AU and temperature ~ 50 K (ref ¹). Such discs are uncommonly bright, far more dense and extensive than the known zodiacal dust in our solar system. Here the emission is concentrated mostly within 1 AU, where the dust temperature is ~ 300K and it is optically very thin, causing an increment of only 10^-5 in the 10 µm luminosity of the Sun as seen from afar.

© 1995 Optical Society of America