H(2)O and OH Gas in the Terrestrial Planet-forming Zones of Protoplanetary Disks

• Published in: The Astrophysical journal Vol. 676; no. 1; pp. L49 - L52
• Main Authors: Salyk, C, Pontoppidan, K M, Blake, G A, Lahuis, F, van Dishoeck, E.F., Evans, N.J.,II
• Format: Journal Article
• Language: English
• Published: 20.03.2008
• ISSN: 0004-637X
• DOI: 10.1086/586894

We present detections of numerous 10-20 urn H(2)O emission lines from two protoplanetary disks around the T Tauri stars AS 205A and DR Tau, obtained using the Infra Red Spectrograph on the Spitzer Space Telescope. Follow-up 3-5 km Keck NIRSPEC data confirm the presence of abundant water and spectrally resolve the lines. We also detect the P4.5 (2.934 km) and P9.5 (3.179 km) doublets of OH and (12)CO/(13)COv = 1 -- 0 emission in both sources. Line shapes and LTE models suggest that the emission from all three molecules originates between 60.5 and 5 AU, and so will provide a new window for understanding the chemical environment during terrestrial planet formation. LTE models also imply significant columns of H(2)O and OH in the inner disk atmospheres, suggesting physical transport of volatile ices either vertically or radially, while the significant radial extent of the emission stresses the importance of a more complete understanding of nonthermal excitation processes.