mountain profile Institute for Astronomy University of Hawaii

Research (the older stuff)



GASPS is a key project on the Herschel Space Observatory. In the coming years, we will obtain far-infrared spectra of ionized carbon, oxygen, and water lines to study the gas content of about 200 circumstellar disks in a variety of clusters of different ages. This will be the first systematic study of the GAS content of Protoplanetary Systems (GASPS) and will reveal their evolution and constrain the timescale for giant planet formation.

The Orion Proplyds

The high frequency, resolution, and sensitivity of the SMA allowed us to make the first mass measurements of protoplanetary disks (proplyds) in Orion in 2005. Since then Rita Mann showed a statistical lack of massive disks in the center of the Trapezium Cluster due to photoevaporation by the massive stars there. However, enough mass remains in their inner, bound regions that their prospects for planet formation appear to be as good as in Taurus and other relatively isolated, low mass star forming environments. She has subsequently found large massive disks beyond the cluster, including the unique massive binary system shown at left.

We are currently expanding the survey and pursuing additional observations to better characterize the nature of the Orion disk population.

Circumstellar Disks

Circumstellar disks funnel material onto a growing star and are the future sites of planet formation. Using the SMA, JCMT, and CSO, Sean Andrews caried out a large survey of disks in Taurus and rho Ophiuchus to measure the distribution of their masses, radial profiles, and grain properties. Ongong work includes higher sensitivity observations to follow later stages of disk evolution and higher resolution studies (~0.2'') to sutdy inner holes and disk clearing, as shown here.

Debris Disks

Planet formation generates small amounts of dusty debris that is detectable in scattered light (left) and in emission at far-infrared to sub-millimeter wavelengths around some nearby main sequence stars. We have undertaken sensitive surveys to examine the timescale over which this process occurs and are beginning to carry out interferometric imaging of the brightest objects to look for dynamical signatures from proto-planets.

Massive Star Formation

Massive stars form in dense packed clusters, shrouded from view at all but the longest wavelengths. Our images of several such regions at high resolution from the mid-infrared to the millimeter using the IRTF and SMA on Mauna Kea have revealed a surprising diversity of protostellar evolutionary states. We are beginning a survey to increase the statistics and learn whether the range of states indicates an extended formation timescale or an environmental dependence.

Molecular Cloud Structure

Molecular clouds have a complex, heirarchical structure, loosely labeled as clumps and cores, that reflects their turbulent dynamics but may also determine the mass distribution of stars. I developed an algorithm, clumpfind, to analyze the structure in the 3-d datasets from spectral line mapping. We are currently using new array cameras on the JCMT, to study cloud structure in unprecendented detail and are developing new algorithms to compare our maps with other datasets and quantify the statistics (or lack of?) on induced star formation.