Structure of the Source I disk in Orion-KL
  This paper analyses images from 43 to 340 GHz to trace the structure of the
Source I disk in Orion-KL with $\sim$12 AU resolution. The data reveal an
almost edge-on disk with an outside diameter $\sim$ 100 AU which is heated from
the inside. The high opacity at 220-340 GHz hides the internal structure and
presents a surface temperature $\sim$500 K. Images at 43, 86 and 99 GHz reveal
structure within the disk. At 43 GHz there is bright compact emission with
brightness temperature $\sim$1300 K. Another feature, most prominent at 99 GHz,
is a warped ridge of emission. The data can be explained by a simple model with
a hot inner structure, seen through cooler material. A wide angle outflow
mapped in SiO emission ablates material from the interior of the disk, and
extends in a bipolar outflow over 1000 AU along the rotation axis of the disk.
SiO $v=0$ $J=5-4$ emission appears to have a localized footprint in the warped
ridge. These observations suggest that the ridge is the working surface of the
disk, and heated by accretion and the outflow. The disk structure may be
evolving, with multiple accretion and outflow events. We discuss two sources of
variability: 1) variable accretion onto the disk as Source I travels through
the filamentary debris from the BN-Source I encounter $\sim$550 yr ago; and 2)
episodic accretion from the disk onto the protostar which may trigger multiple
outflows. The warped inner disk structure is direct evidence that SrcI could be
a binary experiencing episodic accretion.
