Ongoing planet formation around LkCa 15?
C. Thalmann (1), C. A. Grady (2), M. Goto (1), J. P. Wisniewski (3), M. Janson (4), T. Henning (1), M. Fukagawa (5), M. Honda (6), G. D. Mulders (7,8), M. Min (9), A. Moro-Martín (10), M. W. McElwain (11), K. W. Hodapp (12), J. Carson (1, 13), and M. Tamura (14) for the SEEDS team
((1) Max Planck Institute for Astronomy, Heidelberg, Germany, (2) Eureka Scientific and Goddard Space Flight Center, Greenbelt, USA, (3) University of Washington, Seattle, Washington, USA, (4) University of Toronto, Toronto, Canada, (5) Osaka University, Osaka, Japan, (6) Faculty of Science, Kanagawa University, Kanagawa, Japan, (7) Astronomical Institute "Anton Pannekoek", University of Amsterdam, Amsterdam, The Netherlands, (8) SRON Netherlands Institute for Space Research, Groningen, The Netherlands, (9) Astronomical Institute, University of Utrecht, Utrecht, The Netherlands, (10) Department of Astrophysics, CAB - CSIC/INTA, Madrid, Spain, (11) Department of Astrophysical Sciences, Princeton University, Princeton, USA, (12) Institute for Astronomy, University of Hawai`i, Hilo, Hawai`i, USA, (13) College of Charleston, Charleston, South Carolina, USA, (14) National Astronomical Observatory of Japan, Tokyo, Japan)
We report on the recent observational and theoretical advances in the understanding of the pre-transitional disk around LkCa 15, focusing on our high-contrast imaging results obtained with HiCIAO on the Subaru telescope, and discuss their implications on the system architecture and the physical processes shaping it.
The primordial disk of LkCa 15 had previously been shown to be inwardly truncated at a radius of 50 AU on the basis of the spectral energy distribution (SED) and millimeter interferometry. Furthermore, a second dust component was inferred at sub-AU separations, close to the dust sublimation radius, classifying it as a pre-transitional disk. Our H-band images have now resolved the disk gap in the near infrared for the first time. We detect sharp elliptical contours delimiting the nebulosity on the inside as well as the outside, though it remains unclear whether it represents the illuminated inner wall of the outer disk, or forward-scattering on the outer disk surface.
Due to the inner dust component, dynamical clearing has been favored over photoevaporation and magneto-rotational instability as the cause of the disk gap. Our data show a likely physical offset of the disk gap from the star, which reinforces this conclusion. Given the absence of detected companions in the stellar mass regime, the dynamical clearing is most likely due to a freshly formed planetary system.