Multiwavelength Observations of the Candidate Disintegrating sub-Mercury KIC 12557548B

Creators: Croll, Bryce; Rappaport, Saul; DeVore, John; Gilliland, Ronald L.; Crepp, Justin R.; Howard, Andrew W.; Star, Kimberly M.; Chiang, Eugene; Levine, Alan M.; Jenkins, Jon M.; Albert, Loïc; Bonomo, Aldo S.; Fortney, Jonathan J.; Isaacson, Howard

Abstract

We present multiwavelength photometry, high angular resolution imaging, and radial velocities of the unique and confounding disintegrating low-mass planet candidate KIC 12557548b. Our high angular resolution imaging, which includes space-based Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) observations in the optical (~0.53 μm and ~0.77 μm), and ground-based Keck/NIRC2 observations in K' band (~2.12 μm), allow us to rule out background and foreground candidates at angular separations greater than 0".2 that are bright enough to be responsible for the transits we associate with KIC 12557548. Our radial velocity limit from Keck/HIRES allows us to rule out bound, low-mass stellar companions (~0.2 M_☉) to KIC 12557548 on orbits less than 10 yr, as well as placing an upper limit on the mass of the candidate planet of 1.2 Jupiter masses; therefore, the combination of our radial velocities, high angular resolution imaging, and photometry are able to rule out most false positive interpretations of the transits. Our precise multiwavelength photometry includes two simultaneous detections of the transit of KIC 12557548b using Canada-France-Hawaii Telescope/Wide-field InfraRed Camera (CFHT/WIRCam) at 2.15 μm and the Kepler space telescope at 0.6 μm, as well as simultaneous null-detections of the transit by Kepler and HST/WFC3 at 1.4 μm. Our simultaneous HST/WFC3 and Kepler null-detections provide no evidence for radically different transit depths at these wavelengths. Our simultaneous CFHT/WIRCam detections in the near-infrared and with Kepler in the optical reveal very similar transit depths (the average ratio of the transit depths at ~2.15 μm compared with ~0.6 μm is: 1.02 ± 0.20). This suggests that if the transits we observe are due to scattering from single-size particles streaming from the planet in a comet-like tail, then the particles must be ~0.5 μm in radius or larger, which would favor that KIC 12557548b is a sub-Mercury rather than super-Mercury mass planet.

Additional Information

© 2014 American Astronomical Society. Received 2013 December 6. Accepted 2014 March 6. Published 2014 April 22. B.C.'s work was performed under a contract with the California Institute of Technology funded by NASA through the Sagan Fellowship Program. The Natural Sciences and Engineering Research Council of Canada supports the research of B.C. Support for program GO-12987 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555 This work was based on observations at the W. M. Keck Observatory granted by the University of Hawaii and the University of California. We thank the observers who contributed to the measurements reported here and acknowledge the efforts of the Keck Observatory staff. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. The authors thank the referee, Jan Budaj, for helpful comments that have improved this manuscript and for providing us with very convenient tables of indices of refraction for various minerals. The authors especially appreciate the hard work and diligence of the CFHT staff for both scheduling the challenging CFHT observations described here and ensuring these "Staring Mode" observations were successful. The authors thank Geoff Marcy for contributing to and assisting with the Keck/HIRES RV observations of KIC 1255b that we discuss in this work. We also thank Ray Jayawardhana, David Lafreniere, Magali Deleuil, and Claire Moutou for contributing to the CFHT observing proposal, and Josh Winn for contributing to the HST observing proposal, on which this work is partially based.

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