Imaging the Disk around the Luminous Young Star LkHα 101 with Infrared Interferometry

The Herbig Ae/Be star LkHalpha 101 has been imaged at high angular resolutionat a number of wavelengths in the near-infrared (from 1 to 3 microns) using theKeck 1 Telescope, and also observed in the mid-infrared (11.15 microns) usingthe U.C. Berkeley Infrared Spatial Interferometer (ISI). The resolved circulardisk with a central hole or cavity reported in Tuthill et al. (2001) isconfirmed. This is consistent with an almost face-on view (inclination < 35deg) onto a luminous pre- or early-main sequence object surrounded by a massivecircumstellar disk. With a multiple-epoch study spanning almost four years,relative motion of the binary companion has been detected, together withevidence for changes in the brightness distribution of the central disk/star.The resolution of the LkHalpha 101 disk by ISI mid-infrared interferometryconstitutes the first such measurement of a young stellar object in thiswavelength region. The angular size was found to increase only slowly from 1.6to 11.15 microns, inconsistent with standard power-law temperature profilesusually encountered in the literature, supporting instead models with a hotinner cavity and relatively rapid transition to a cool or tenuous outer disk.The radius of the dust-free inner cavity is consistent with a model ofsublimation of dust in equilibrium with the stellar radiation field.Measurements from interferometry have been combined with published photometryenabling an investigation of the energetics and fundamental properties of thisprototypical system.Comment: Appearing in Astrophysical Journal. 24 pages; 8 figure