NOAO >   Observing Info >   Approved Programs >   2013B-0225

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Proposal Information for 2013B-0225


PI: John Carr, Naval Research Laboratory, carr@nrl.navy.mil
Address: Code 7211, 4555 Overlook Ave., SW, Washington, DC 20375

CoI: Joan Najita, NOAO
CoI: Matt Richter, UC Davis
CoI: Colette Salyk, NOAO
CoI: John Lacy, Univ Texas
CoI: Curtis deWitt, UC Davis

Title: Molecular Shielding and Photodissociation of H_2O in the Disks of T Tauri Stars

Abstract: The abundant water vapor in the atmospheres of the inner disks of T Tauri stars is likely to play a central role in both the chemistry and thermodynamics of the inner disk. The known column densities of water are sufficiently large for water to be self-shielding to the photo- dissociating FUV radiation. This shielding process can protect deeper layers in the disk from the effects of harsh FUV radiation and foster the synthesis of organic molecules. We will obtain high-resolution mid- infrared spectra of OH and H_2O in order to demonstrate the action of water self-shielding in the disk atmosphere. Direct measurements of the OH (Lambda)-doublet ratio will be made as a diagnostic of the formation pathway of OH. In addition, velocity resolved spectra of OH and H_2O will be used to determine if they have similar kinematics, and hence, the same spatial distribution. These data will test our hypothesis that rotationally hot OH emission in TTS spectra is evidence of the photodissociation of water and molecular shielding at the disk surface.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2013B-0225

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