AAS 203rd Meeting, January 2004
Session 33 Young Stars
Oral, Monday, January 5, 2004, 2:00-3:30pm, Regency VII

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[33.01] Probing the Inner Disk around Young Stars with High-resolution NIR Spectroscopy

S. D. Brittain (University of Notre Dame)

Planet formation is intimately associated with the accretion and evolution of gas and dust in disks around young stars. A comprehensive understanding of the physics and chemistry of young circumstellar disks is therefore essential to a complete picture of star and planet formation, yet basic questions remain unanswered. High resolution near infrared spectroscopy has an important role to play in characterizing the planet-forming region around young stars. In particular, we use high-resolution near infrared spectroscopy to address the following issues:

1) How long does gas survive in the inner disk?

We present near infrared high-resolution spectra of CO from the circumstellar protoplanetary region around young stars. The spectra are compared to the spectral energy distribution for each star. The CO observations are used to determine the mass, density and temperature of the gas around the star and the spectral energy distribution is used to gauge the evolutionary status of the dust disk. Implications for the evolution of the disk and subsequent planet formation will be discussed.

2) Is there any evidence of gas/dust stratification in the disk?

Gas and dust mixing in the extended disk around a young star is one of the most debated and untested results of theoretical modeling in recent years. Theoretical models of dust/gas mixing in the disk are at odds but the predictions set the stage for observations to guide our ideas of planet formation. The vertical distribution of dust and gas in disks can be assessed by simultaneous comparison of infrared CO absorption lines with infrared extinction. We will present results for 12CO, 13CO, and C18O line absorption in young disks. Interestingly, the dust extinction is insufficient to explain the very large columns of absorbing gas. The most straightforward interpretation of the existing data confirms the stratification of dust and gas in circumstellar disks.

The author(s) of this abstract have provided an email address for comments about the abstract: sbrittai@nd.edu

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.