Dr. Eric L. N. Jensen
Physics and Astronomy Department
Swarthmore College
More than 80% of Sun-like stars are surrounded at birth by orbiting disks of gas and dust like the one that formed the planets in our solar system. Most of these stars have lost any observable trace of this protoplanetary material by an age of three million years, much shorter than the commonly-cited theoretical timescale of 8-10 million years for the formation of giant planets. Have these stars already formed planets on a much shorter timescale? Or does rapid disk dispersal mean that planet formation is a rare event? I will discuss my studies of disk evolution around young stars, and how these data may give us insight into planet formation mechanisms. In particular, I will focus on DoAr 21, a low-mass star that has already lost its disk at an age of less than 1 Myr, but which is still illuminating circumstellar gas with intense UV radiation; and on lithium depletion in low-mass stars, which may help us identify young stars of planet-forming age that are far from known star-forming regions.
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