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J.S. Bary (Vanderbilt University)
Dating back to the 1700s, planetary formation theory has been rooted in the idea that our solar system formed from a cloud of gas and dust, which orbited the Sun during its birth. Since the only remnants of the theorized nebula are the planets, moons, comets, asteroids, etc., evidence supporting the ``nebular hypothesis'' awaited the discovery of analogs of the solar nebula. Some 200 years later, we now have optical and infrared images among a variety of observations that demonstrate the presence of such nebulae orbiting most Sun-like stars less than 3~Myr old. However, modern core accretion theory of planet formation has stumbled due to the timescales predicted to be necessary to form planets and the lifespan of disks based upon observations of gas tracers such as dust and CO line emission. The disappearance of gas tracers may not indicate the dissipation of the disk, but also may be interpreted as a signature of on-going planet formation. Although H2 comprises 70% of the mass of circumstellar disks and will be the last component of the circumstellar disk to be collected into planets, it is notoriously difficult to detect, which is the reason astronomers have relied on tracer emission to detect and study these disks. In order to determine whether the disk persists once dust emission is no longer detectable, observations of H2 are required. Spectroscopic observations capable of detecting small amounts (10-10~M\odot) of H2 emission were conducted in search of possible emission from H2 gas residing in an otherwise undetectable disk. The results of these observations will be presented and the location of the emitting gas will be discussed in the context of possible stimulation mechanisms.
The author(s) of this abstract have provided an email address for comments about the abstract: jeff.bary@vanderbilt.edu
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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.