EQUILIBRIUM TEMPERATURE OF ICE GRAINS FORMED AROUND A STAR AS A FUNCTION OF STELLAR PARAMETERS

We present theoretical equilibrium temperatures of water ice spheres assumed in orbit around a star as a function the star parameters, distance to the grain, and grain radius. The results are reliable up to stellar temperatures of ~ 60 000K. They show that the minimum in "grain" temperature predicted for solar system ice near 60 µm in radius is a general property, and that grains of any size have a minimal temperature around 10 000 K stars. The implications of the results on the past thermal history of solar system ices and the detectability of ices around other stars are briefly discussed