Authors

C. Grady (1), G. Schneider (2), M. Sitko (3) and the HST-GO-10177 Team

Affiliations

(1) Eureka Scientific and GSFC; (2) U. of Arizona; (3) U. Cincinnati

Abstract

We present a reanalysis of archival HST coronagraphic imagery of the young Solar analog LkCa 15’s outer disk. The disk is robustly detected to 200 AU, before deprojection by HST/NICMOS at 1.1 microns, and less robustly by HST/STIS to 140 AU, well beyond the recently reported cavity. For protoplanetary disks at these distances from the star, mild surface brightness asymmetries (typically 3:1) are seen along the system semi-major axis, with the bright side of the disk the near side of the disk. LkCa 15’s outer disk is brightest along the side identified as the near side from millimeter interferometry. However, we find an unusually large range in surface brightness from the near to far side of the disk, and along the system major axis which is inconsistent with viewing geometry and with grain scattering effects. We discuss modeling of the outer disk in the context of zonal shadowing or developing structure which may be a precursor to the more complete clearing of the disk seen interior to 50 AU.