ANOTHER CHANCE TO HEAR ALL ABOUT DISK EVOLUTION AND THE ORIGINS OF
PLANETS

Vince Mannings
Jet Propulsion Laboratory

Homepage: http://astro.caltech.edu/~vgm

This talk is aimed mainly at people who missed my earlier colloquium
in November 1999.  New results will be presented from a long-term
quantitative analysis of interferometric millimeter-wave images of the
grain and gas components of disks around young stars (t < 10
Myr). Both single-dish observations and high spatial resolution
interferometric studies of disks suggest that these massive, dense and
long-lived orbiting reservoirs of material support the growth of
grains, rocks, planetesimals and planets.  Results will also be
presented from ongoing studies of second-generation debris disks
around main-sequence stars (t > 100 Myr).  By carefully charting the
evolution of disk environments, we probe the sequence of events
leading to the formation of planets and, by extension, we gain insight
to the physical processes by which our own planetary system emerged
from the young solar nebula.

Much work remains to be done. We find that disks survive as gas-rich
structures with masses up to one tenth of a solar mass until about 10
Myr, while the older gas-free debris disks contain maybe a lunar mass
of grains. The final and important stages of planet formation must
therefore occur within the intervening age span of 10 to 100 Myr, yet
this phase of disk evolution has barely been explored. Mauna Kea's new
submillimeter interferometer (the SMA) and the new generation of
mid-IR cameras will be crucial to closing these gaps in our knowledge
of disk evolution.