Joint Astrophysics Colloquium

Circumstellar Debris Disks — What Can Be Learned

Yanqin Wu

University of Toronto

Around 20% of all stars have detectable infrared excesses in the 70 micron Spitzer bands. These excesses have brightnesses of order 10^-5 - 10^-3 of the stellar luminosities and decay slowly as the stars age. They arise from thermal re-radiation of small dust particles (microns to millimeters) orbiting the stars at distances similar to that of our Kuiper belt. Larger bodies must be present in these disks to continuously produce the dust particles. These bodies are intimately related to late stages of planet formation, but their properties can only be indirectly inferred. In contrast, the largest bodies in our Kuiper belt are observed, while its associated dusty disk is below detection and is believed to be thousand times less luminous than the Spitzer disks. I will report our progress on this and other issues related to circumstellar debris disks.