Validation of 12 small Kepler transiting planets in the habitable zone

Torres, Guillermo and Kipping, David M. and Fressin, Francois and Caldwell, Douglas A. and Twicken, Joseph D. and Ballard, Sarah and Batalha, Natalie M. and Bryson, Stephen T. and Ciardi, David R. and Henze, Christopher E. and Howell, Steve B. and Isaacson, Howard T. and Jenkins, Jon M. and Muirhead, Philip S. and Newton, Elisabeth R. and Petigura, Erik A. and Barclay, Thomas and Borucki, William J. and Crepp, Justin R. and Everett, Mark E. and Horch, Elliott P. and Howard, Andrew W. and Kolbl, Rea and Marcy, Geoffrey W. and McCauliff, Sean and Quintana, Elisa V. (2015) Validation of 12 small Kepler transiting planets in the habitable zone. The Astrophysical Journal, 800 (2). pp. 99-122. ISSN 0004-637X

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We present an investigation of 12 candidate transiting planets from Kepler with orbital periods ranging from 34 to 207 days, selected from initial indications that they are small and potentially in the habitable zone (HZ) of their parent stars. Few of these objects are known. The expected Doppler signals are too small to confirm them by demonstrating that their masses are in the planetary regime. Here we verify their planetary nature by validating them statistically using the BLENDER technique, which simulates large numbers of false positives and compares the resulting light curves with the Kepler photometry. This analysis was supplemented with new follow-up observations (high-resolution optical and near-infrared spectroscopy, adaptive optics imaging, and speckle interferometry), as well as an analysis of the flux centroids. For 11 of them (KOI-0571.05, 1422.04, 1422.05, 2529.02, 3255.01, 3284.01, 4005.01, 4087.01, 4622.01, 4742.01, and 4745.01) we show that the likelihood they are true planets is far greater than that of a false positive, to a confidence level of 99.73% (3σ) or higher. For KOI-4427.01 the confidence level is about 99.2% (2.6σ). With our accurate characterization of the GKM host stars, the derived planetary radii range from 1.1 to 2.7 R ⊕. All 12 objects are confirmed to be in the HZ, and nine are small enough to be rocky. Excluding three of them that have been previously validated by others, our study doubles the number of known rocky planets in the HZ. KOI-3284.01 (Kepler-438b) and KOI-4742.01 (Kepler-442b) are the planets most similar to the Earth discovered to date when considering their size and incident flux jointly.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Access to published version in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 02 Jun 2017 06:14
Last Modified: 27 Jun 2017 00:28
Uncontrolled Keywords: methods: statistical; planetary systems; stars: individual (KOI-3284 (Kepler-438), KOI-4742 (Kepler-442)); techniques: photometric;
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
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