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We present H- and Ks-band imaging data resolving the gap in the transitionaldisk around LkCa 15, revealing the surrounding nebulosity. We detect sharpelliptical contours delimiting the nebulosity on the inside as well as theoutside, consistent with the shape, size, ellipticity, and orientation ofstarlight reflected from the far-side disk wall, whereas the near-side wall isshielded from view by the disk's optically thick bulk. We note thatforward-scattering of starlight on the near-side disk surface could provide analternate interpretation of the nebulosity. In either case, this discoveryprovides confirmation of the disk geometry that has been proposed to explainthe spectral energy distributions (SED) of such systems, comprising anoptically thick outer disk with an inner truncation radius of ~46 AU enclosinga largely evacuated gap. Our data show an offset of the nebulosity contoursalong the major axis, likely corresponding to a physical pericenter offset ofthe disk gap. This reinforces the leading theory that dynamical clearing by atleast one orbiting body is the cause of the gap. Based on evolutionary models,our high-contrast imagery imposes an upper limit of 21 Jupiter masses oncompanions at separations outside of 0.1" and of 13 Jupiter masses outside of0.2". Thus, we find that a planetary system around LkCa 15 is the most likelyexplanation for the disk architecture.

Imaging of a Transitional Disk Gap in Reflected Light: Indications of Planet Formation Around the Young Solar Analog LkCa 15