Revision of Earth-sized Kepler Planet Candidate Properties with High Resolution Imaging by Hubble Space Telescope

Abstract

We present the results of our Hubble Space Telescope program and describe how our analysis methods were used to re-evaluate the habitability of some of the most interesting Kepler planet candidates. Our program observed 22 Kepler Object of Interest (KOI) host stars, several of which were found to be multiple star systems unresolved by Kepler. We use our high-resolution imaging to spatially resolve the stellar multiplicity of Kepler-296, KOI-2626, and KOI-3049, and develop a conversion to the Kepler photometry (Kp) from the F555W and F775W filters on WFC3/UVIS. The binary system Kepler-296 (5 planets) has a projected separation of 0.217" (80AU); KOI-2626 (1 planet candidate) is a triple star system with a projected separation of 0.201" (70AU) between the primary and secondary components and 0.161" (55AU) between the primary and tertiary; and the binary system KOI-3049 (1 planet candidate) has a projected separation of 0.464" (225AU). We use our measured photometry to fit the separated stellar components to the latest Victoria-Regina Stellar Models with synthetic photometry to conclude that the systems are coeval. The components of the three systems range from mid-K dwarf to mid-M dwarf spectral types. We solved for the planetary properties of each system analytically and via an MCMC algorithm using our independent stellar parameters. The planets range from ~1.6R_Earth to ~4.2R_Earth, mostly Super Earths and mini-Neptunes. As a result of the stellar multiplicity, some planets previously in the Habitable Zone are, in fact, not, and other planets may be habitable depending on their assumed stellar host.

16 pages, 10 figures, ApJ, 804, 97

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Cited by in corpus (9)

• The Kepler Follow-Up Observation Program. I. A Catalog of Companions to Kepler Stars from High-Resolution Imaging
• A Catalog of Kepler Habitable Zone Exoplanet Candidates
• Unresolved Binary Exoplanet Host Stars Fit as Single Stars: Effects on the Stellar Parameters
• Updated Catalog of Kepler Planet Candidates: Focus on Accuracy and Orbital Periods
• Stellar Companions to the Exoplanet Host Stars HD 2638 and HD 164509
• Kepler Transit Depths Contaminated by a Phantom Star
• Exclusion of Stellar Companions to Exoplanet Host Stars
• Revising Properties of Planet-host Binary Systems I.: Methods and Pilot Study
• Revising Properties of Planet-host Binary Systems II: Apparent Near-Earth Analog Planets in Binaries Are Often Sub-Neptunes