A Closer Look at the LkCa 15 Protoplanetary Disk
  We present 870 micron observations of dust continuum emission from the LkCa
15 protoplanetary disk at high angular resolution (with a characteristic scale
of 0.25" = 35 AU), obtained with the IRAM Plateau de Bure interferometer and
supplemented by slightly lower resolution observations from the Submillimeter
Array. We fit these data with simple morphological models to characterize the
spectacular ring-like emission structure of this disk. Our analysis indicates
that a small amount of 870 micron dust emission (~5 mJy) originates inside a
large (40-50 AU radius) low optical depth cavity. This result can be
interpreted either in the context of an abrupt decrease by a factor of ~5 in
the radial distribution of millimeter-sized dust grains or as indirect evidence
for a gap in the disk, in agreement with previous inferences from the
unresolved infrared spectrum and scattered light images. A preliminary model
focused on the latter possibility suggests the presence of a low-mass
(planetary) companion, having properties commensurate with those inferred from
the recent discovery of LkCa 15b.
