Karl Stapelfeldt 1, Andrea Moneti 2, Michael Meyer 3, & Christopher Burrows 4
1 Mail Stop 183-9, Jet Propulsion Laboratory
2 ISO Science Operations Centre 3 Steward Observatory
4 Space Telescope Science Institute
HH 30 is a prototype young stellar object (YSO) accretion disk system located in the nearby L1551 molecular cloud. HST images reveal that HH 30 appears as an edge-on optically thick circumstellar absorption disk, 450 AU in diameter, and extending perpendicular to highly collimated bipolar jets. HH 30 is the first YSO disk to have its vertical structure clearly resolved, and presents a unique opportunity to combine our understanding of a disk's geometry and its spectral energy distribution (SED). New photometry using CAM and PHT have been obtained over the wavelength range of 5-90 microns, filling important gaps in the observed SED of this object. We find that the SED is double-peaked, with one peak at 2 microns and a second somewhere beyond 60 microns. A weak silicate absorption feature may be present. The decline in the SED between 2 and 14 microns is quite unusual for a YSO disk, and appears best explained by self-absorption of the disk's thermal emission resulting in the system being dominated by scattered light in the mid-infrared. At 25 microns the SED rises again as the disk emission at last penetrates the extinction. The consequences of these results for the density and temperature distribution in the HH 30 disk will be discussed.