RX J1852.3-3700 is a nearby 10 Myr old 1.1 Msol T Tauri star, harbouring a well-characterized transitional disk with an inner hole in its dust disk corresponding to the Saturn-Uranus zone in our own solar system. Based on observational constraints on the CO and H2 gas mass, the disk is likely in the process of gas clearing. As part of our Herschel program to search for remnant gas in well-studied 10--150 Myr disk systems, we have recently detected [OI] 63 micron in this disk. Based on the thermo-chemical disk models of Gorti & Hollenbach (2004), we have identified two possible disk configurations that could explain the observed [OI], are consistent with the non-detections of CO and H2, and that differ significantly in predicted radial extent, gas masses, inferred gas-to-dust ratios, which point at different scenarios for gas dispersal and prospects for planet formation. We propose to obtain deep PACS spectroscopy of the [CII] 158 micron line, with the goal of constraining the spatial extent of the gas distribution, and thus discriminate between the two scenarios.
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.