The Disk and Environment of a Young AltairAnalog: SAO 206462

摘要

Proto-planetary and transitional disks which are detected in scattered light provide a criti-cal test of the interpretation of circumstellar disks based on the IR spectral energy distribution (SED)alone. The disk inclination to the line-of-sight, outter radius, and surface brightness (SB) maps orradial SB distributions provided by spatially resolved imaging remove most of the degeneracies in-herent in fitting IR SEDs without such observational constraints. We have imaged the disk of SAO206462 (HD 135344B) in 1.1 and 1.6μm scattered light with HST/NICMOS and can trace the es-sentially face-on disk out to 1.05". The cavity detected in sub-mm observations lies entirely underthe NICMOS coronagraphic spot, a result consistent with the SED fitting if the star is at d=140pc.The SED had previously been classified as a Meeus Group I SED and interpreted as arising in aflared disk. Neither the 1.1 nor the 1.6μm radial surface brightness profiles are consistent with aflared disk. A FUSE FUV spectrum demonstrates the presence of excess light in this system, con-firming the accretion rate estimated from Bry. Collectively, these data strengthen the interpretationof this system as a transitional disk.