  We have measured continuum flux densities of a high-mass protostar candidate,
a radio source I in the Orion KL region (Orion Source I) using the Atacama
Large Millimeter/Submillimeter Array (ALMA) at band 8 with an angular
resolution of 0.1". The continuum emission at 430, 460, and 490 GHz associated
with Source I shows an elongated structure along the northwest-southeast
direction perpendicular to the so-called low-velocity bipolar outflow. The
deconvolved size of the continuum source, 90 au times 20 au, is consistent with
those reported previously at other millimeter/submillimeter wavelength. The
flux density can be well fitted to the optically thick black-body spectral
energy distribution (SED), and the brightness temperature is evaluated to be
700-800 K. It is much lower than that in the case of proton-electron or H-
free-free radiations. Our data are consistent with the latest ALMA results by
Plambeck & Wright (2016), in which the continuum emission have been proposed to
arise from the edge-on circumstellar disk via thermal dust emission, unless the
continuum source consists of an unresolved structure with the smaller beam
filling factor.
