Adam Kraus

Title: The Demographics of Young Planetary Systems

Abstract: Young and directly-imaged exoplanets offer critical tests of
planet-formation models that can't be matched by RV surveys of mature
stars. However, these targets have been extremely elusive to date,
with no exoplanets younger than ~10-20 Myr and only a handful of
direct-imaged exoplanets at all ages. I will present emerging results
from three ongoing programs (in increasing order of optimism) that
exploit a new technique, aperture-mask interferometry, to study the
demographics and properties of young extrasolar planetary systems.

First, based on a synthesis of disk and multiplicity surveys, I will
establish what types of stars probably should not be expected to
host extrasolar planets. I will then describe the discovery of several
extremely low-mass companions in wide orbits around young stars; as I
will discuss, these intriguing companions appear to be planetary in
mass, but are more likely to form like stars or brown dwarfs than like
bona fide "planets". Finally, I will present the first result from a
new survey to directly search for young analogs to our own solar
system (i.e. gas giants at 5-30 AU). While observing a young star with
a known gap in its disk, our team discovered a young exoplanet
embedded in the middle of that gap. Given the substantial mass of the
circumstellar disk and the very red colors of the planet, I propose
that the planet is actively accreting its gaseous envelope via a
circumplanetary disk or shell, and thus that it has been caught at
formation