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

The Herbig Ae/Be star LkHα 101 has been imaged at high angular resolution at a number of wavelengths in the near-infrared (from 1 to ~3 μm), using the Keck I Telescope, and also observed in the mid-infrared (11.15 μm), using the UC Berkeley Infrared Spatial Interferometer (ISI). The resolved circular disk with a central hole or cavity reported by Tuthill, Monnier, & Danchi is confirmed. This is consistent with an almost face-on view (inclination of 35°) onto a luminous pre-main-sequence or early main-sequence object surrounded by a massive circumstellar disk. With a multiple-epoch study spanning almost 4 years, relative motion of the binary companion has been detected, together with evidence of changes in the brightness distribution of the central disk/star. The resolution of the LkHα 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 μm, 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.

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