Evidence for Dust Grain Growth in Young Circumstellar Disks
Henry B. Throop,1*
John Bally,2
Larry W. Esposito,1
Mark
J. McCaughrean3
Hundreds of circumstellar disks in the Orion nebula are
being rapidly destroyed by the intense ultraviolet radiation produced by nearby bright stars. These young, million-year-old disks may not
survive long enough to form planetary systems. Nevertheless, the first
stage of planet formation--the growth of dust grains into larger
particles--may have begun in these systems. Observational evidence for
these large particles in Orion's disks is presented. A model of grain
evolution in externally irradiated protoplanetary disks is developed
and predicts rapid particle size evolution and sharp outer disk
boundaries. We discuss implications for the formation rates of
planetary systems.
1 Laboratory for Atmospheric and Planetary Sciences,
University of Colorado, Boulder, CO 80309-0392, USA.
2 CASA, University of Colorado, Boulder, CO 80309-0389,
USA.
3 Astrophysikalisches Institut Potsdam, An der
Sternwarte 16, D-14482 Potsdam, Germany.
*
Present address: Southwest Research Institute, 1050 Walnut
Street, Suite 426, Boulder, CO 80302, USA. E-mail:
throop{at}boulder.swri.edu
