Art by Paul Kalas
Origin Comet Jewitt
Debris Disks

Many stars less than a few million years old show evidence for circumstellar dust, often in the form of a disk. This is thought to be material in the final stages of accretion, perhaps connected with the growth of planets and comets around these stars. Much older, main-sequence, stars also sometimes possess circumstellar dust disks. Three examples are shown in the panel at left.

Our own sun possesses a tenuous disk (the "Zodiacal Cloud") caused by dust released from active comets and colliding asteroids. Beta Pictoris and BD+31 643 are other examples. In these stars, the dust lifetime is less than the age of the star, indicating that the dust has been recently created.

Possible mechanisms for dust production include collisional grinding of asteroids and comets in unseen Kuiper Belts, and ejection of dust from star-grazing comets.


Candidate Circumstellar Disk Around BD +31 643