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[13.10] Observation of CO Absorption Toward Young Stars: Test of Disk Stratification

T. W. Rettig, S. D. Brittain (University of Notre Dame), T Simon (University of Hawaii), C. Kulesa (University of Arizona)

The degree of gas/dust mixing in the disk around young stellar objects is an important factor for models of planet formation, but it has not been observationally tested. Similarly, whether or not the dust settles to the mid-plane faster than the gas, leading to a stratified disk, is an open theoretical question. Understanding the vertical structure of the disk will provide constraints on the various planet formation scenarios. We have measured the column densities of the gas phase molecules 12CO, 13CO, and C18O around pre-main sequence stars having various extinctions and inclinations. Our initial results indicate that as the inclination of the disk mid-plane increases from the line of sight, the measured dust extinction becomes insufficient to explain the column of absorbing gas. The most straightforward interpretation of the data suggests the stratification of dust and gas in circumstellar disks. This work is supported by NSF Astronomy.

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