Deep 24 Micron Imaging of Nearby Debris Disks Around A Stars

Although it is the prototypical debris disk, Spitzer observations of Vega reveal the most unexpected phenomenon of debris consisted of small grains streaming out of the system by radiation pressure and forming a very extended disk. The very short lifetime and the amount of small grains suggest recent major collision events have produced a cloud of very fine dust that is now being ejected from the Vega system. The discovery around Vega suggests a major shift in the way we model debris disks. Understanding the prevalence of debris systems similar to that of Vega (dominated by the consequence of recent major events) will have a major influence on our interpretation of the large number of Spitzer observations of debris disks. We have obtained deep (2000 sec) 24 micron images of 15 A-type debris disks where such behavior can be detected with Spitzer. Combined with previous observations of Vega, Fomalhaut and beta Pictoris, our sample will give us a first-order understanding of the occurrence of Vega-like behavior. A detail discussion will be presented in this paper.

Support for this work was provided by NASA through Contract Number 1276192 issued by JPL/Caltech.