AAS 202nd Meeting, May 2003
Session 24 When Do Planets Form?
Topical Oral, Tuesday, May 27, 2003, 8:30-10:00am and 10:45am-12:30pm, 204

## [24.04] Gas emission from optically thin dust disks

U. Gorti (NASA Ames/UC Berkeley), D. Hollenbach (NASA Ames)

We present the results of detailed thermo-chemical modelling of small amounts of gas (0.01 to 10 M\rm J) in optically thin dust disks, with dust masses in small (a<1 mm) particles ranging from 3 \times 10-5 to 0.3 M\rm E. We self-consistently solve for the temperature and vertical density structure of the inner planet-forming regions of a gas disk heated by processes such as collisions with warm dust grains, FUV pumping of molecular hydrogen and stellar X-rays. The gas radiates strongly in various infrared lines (e.g. SI(25\mum), H2(12\mum, 17\mum, 28\mum), several OH and H2O lines) which could provide an important diagnostic for the presence of gas in disks and the physical and chemical conditions in the disk. We discuss the possibility of detection by SIRTF of small amounts of gas (\gtrsim 0.1 M\rm J) in disks by analyzing expected line fluxes and line to continuum ratios.