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Validation of Small Kepler Transiting Planet Candidates in or near the Habitable Zone

Torres, Guillermo and Kane, Stephen R. and Rowe, Jason F. and Batalha, Natalie M. and Henze, Christopher E. and Ciardi, David R. and Barclay, Thomas and Borucki, William J. and Buchhave, Lars A. and Crepp, Justin R. and Everett, Mark E. and Horch, Elliott P. and Howard, Andrew W. and Howell, Steve B. and Isaacson, Howard T. and Jenkins, Jon M. and Latham, David W. and Petigura, Erik A. and Quintana, Elisa V. (2017) Validation of Small Kepler Transiting Planet Candidates in or near the Habitable Zone. Astronomical Journal, 154 (6). Art. No. 264. ISSN 1538-3881.

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A main goal of NASA's Kepler Mission is to establish the frequency of potentially habitable Earth-size planets (η⊕). Relatively few such candidates identified by the mission can be confirmed to be rocky via dynamical measurement of their mass. Here we report an effort to validate 18 of them statistically using the BLENDER technique, by showing that the likelihood they are true planets is far greater than that of a false positive. Our analysis incorporates follow-up observations including high-resolution optical and near-infrared spectroscopy, high-resolution imaging, and information from the analysis of the flux centroids of the Kepler observations themselves. Although many of these candidates have been previously validated by others, the confidence levels reported typically ignore the possibility that the planet may transit a star different from the target along the same line of sight. If that were the case, a planet that appears small enough to be rocky may actually be considerably larger and therefore less interesting from the point of view of habitability. We take this into consideration here and are able to validate 15 of our candidates at a 99.73% (3σ) significance level or higher, and the other three at a slightly lower confidence. We characterize the GKM host stars using available ground-based observations and provide updated parameters for the planets, with sizes between 0.8 and 2.9 R⊕. Seven of them (KOI-0438.02, 0463.01, 2418.01, 2626.01, 3282.01, 4036.01, and 5856.01) have a better than 50% chance of being smaller than 2 R⊕ and being in the habitable zone of their host stars.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Torres, Guillermo0000-0002-5286-0251
Kane, Stephen R.0000-0002-7084-0529
Rowe, Jason F.0000-0002-5904-1865
Ciardi, David R.0000-0002-5741-3047
Barclay, Thomas0000-0001-7139-2724
Buchhave, Lars A.0000-0003-1605-5666
Crepp, Justin R.0000-0003-0800-0593
Everett, Mark E.0000-0002-0885-7215
Horch, Elliott P.0000-0003-2159-1463
Howard, Andrew W.0000-0001-8638-0320
Howell, Steve B.0000-0002-2532-2853
Isaacson, Howard T.0000-0002-0531-1073
Jenkins, Jon M.0000-0002-4715-9460
Latham, David W.0000-0001-9911-7388
Petigura, Erik A.0000-0003-0967-2893
Additional Information:© 2017 The American Astronomical Society. Received 2017 August 11; revised 2017 November 1; accepted 2017 November 1; published 2017 December 1. We thank the anonymous referee for helpful comments on the original manuscript. This paper includes data collected by the Kepler spacecraft. Funding for the Kepler Mission is provided by NASA's Science Mission Directorate. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center. The research has also made use of NASA's Astrophysics Data System (ADS) and of data products from the Mikulski Archive for Space Telescopes (MAST). Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Maunakea we are privileged to be guests. G.T. acknowledges partial support for this work from NASA grant NNX14AB83G (Kepler Participating Scientist Program) and Cooperative Agreement NNX13AB58A with the Smithsonian Astrophysical Observatory (PI: D.W.L.). This research was enabled in part by support provided by Calcul Québec ( and Compute Canada (
Group:Astronomy Department
Funding AgencyGrant Number
Subject Keywords:methods: statistical – planetary systems – stars: individual (KOI-0172.02 = Kepler-69c ...) – techniques: photometric
Issue or Number:6
Record Number:CaltechAUTHORS:20171130-103943491
Persistent URL:
Official Citation:Guillermo Torres et al 2017 AJ 154 264
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83597
Deposited By: Tony Diaz
Deposited On:30 Nov 2017 18:56
Last Modified:03 Oct 2019 19:08

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