  The Herbig Ae/Be star LkHalpha 101 has been imaged at high angular resolution
at a number of wavelengths in the near-infrared (from 1 to 3 microns) using the
Keck 1 Telescope, and also observed in the mid-infrared (11.15 microns) using
the U.C. Berkeley Infrared Spatial Interferometer (ISI). The resolved circular
disk with a central hole or cavity reported in Tuthill et al. (2001) is
confirmed. This is consistent with an almost face-on view (inclination < 35
deg) onto a luminous pre- or early-main sequence object surrounded by a massive
circumstellar disk. With a multiple-epoch study spanning almost four years,
relative motion of the binary companion has been detected, together with
evidence for changes in the brightness distribution of the central disk/star.
The resolution of the LkHalpha 101 disk by ISI mid-infrared interferometry
constitutes the first such measurement of a young stellar object in this
wavelength region. The angular size was found to increase only slowly from 1.6
to 11.15 microns, inconsistent with standard power-law temperature profiles
usually encountered in the literature, supporting instead models with a hot
inner 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 of
sublimation of dust in equilibrium with the stellar radiation field.
Measurements from interferometry have been combined with published photometry
enabling an investigation of the energetics and fundamental properties of this
prototypical system.
