2002 Annual Science Report
University of Colorado, Boulder Reporting | JUL 2001 – JUN 2002
The Formation of Planets Around Young Stars
We continue to analyze the formation and evolution of proto-planetary disks in the typical environment where most stars are born. We have found evidence for large grains in one of the proto-planetary disks embedded within the Orion Nebula. We made the first detection of the large silhouette disk in Orion known as 114-426 in 4.05 µm Brackett α line, finding evidence for a turnover in the grain size distribution near a size of 4 µm. We used the Keck 1 telescope and its adaptive optics system to obtain 0.05 images and spectra of several bright proto-planetary disks. We discovered the first candidate proto-planetary disks and proplyds, in the eta-Carina nebula, a region that is bathed in ultraviolet (UV) light about 100 times more intense than found in the Orion Nebula. We have continued to model the growth of grains into macroscopic particles. We have argued that 90% of field stars are born sufficiently close to massive stars to have their disks influenced by intense UV radiation. UV destroys disks in typically less than 1 million years. Therefore, planet formation must either be prompt, or planetary systems with architectures similar to the Solar system will turn out to be relatively rare.
I have initiated a program to explore the likely architectures of planetary systems formed in various types of star forming regions. I am also attempting to refine the estimates of the fraction of stars formed in the various types of star forming regions such as dark clouds where UV radiation is not an issue and irradiated environments such as the Orion Nebula or the eta-Carina nebula. I am also investigating the hazards to planet formation resulting from the interactions of protostars with their sibling stars in regions of clustered star formation.