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Contamination in the Kepler Field. Identification of 685 KOIs as False Positives Via Ephemeris Matching Based On Q1-Q12 Data

Coughlin, Jeffrey L. and Thompson, Susan E. and Bryson, Stephen T. and Burke, Christopher J. and Caldwell, Douglas A. and Christiansen, Jessie L. and Haas, Michael R. and Howell, Steve B. and Jenkins, Jon M. and Kolodziejczak, Jeffery J. and Mullally, Fergal R. and Rowe, Jason F. (2014) Contamination in the Kepler Field. Identification of 685 KOIs as False Positives Via Ephemeris Matching Based On Q1-Q12 Data. Astronomical Journal, 147 (5). Art. No. 119. ISSN 0004-6256. http://resolver.caltech.edu/CaltechAUTHORS:20140529-075408143

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Abstract

The Kepler mission has to date found almost 6000 planetary transit-like signals, utilizing three years of data for over 170,000 stars at extremely high photometric precision. Due to its design, contamination from eclipsing binaries, variable stars, and other transiting planets results in a significant number of these signals being false positives (FPs). This directly affects the determination of the occurrence rate of Earth-like planets in our Galaxy, as well as other planet population statistics. In order to detect as many of these FPs as possible, we perform ephemeris matching among all transiting planet, eclipsing binary, and variable star sources. We find that 685 Kepler Objects of Interest (KOIs)—12% of all those analyzed—are FPs as a result of contamination, due to 409 unique parent sources. Of these, 118 have not previously been identified by other methods. We estimate that ~35% of KOIs are FPs due to contamination, when performing a first-order correction for observational bias. Comparing single-planet candidate KOIs to multi-planet candidate KOIs, we find an observed FP fraction due to contamination of 16% and 2.4% respectively, bolstering the existing evidence that multi-planet KOIs are significantly less likely to be FPs. We also analyze the parameter distributions of the ephemeris matches and derive a simple model for the most common type of contamination in the Kepler field. We find that the ephemeris matching technique is able to identify low signal-to-noise FPs that are difficult to identify with other vetting techniques. We expect FP KOIs to become more frequent when analyzing more quarters of Kepler data, and note that many of them will not be able to be identified based on Kepler data alone.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-6256/147/5/119DOIArticle
http://iopscience.iop.org/1538-3881/147/5/119/PublisherArticle
http://arxiv.org/abs/1401.1240arXivDiscussion Paper
http://dx.doi.org/10.1088/0004-6256/147/6/163PublisherErratum
ORCID:
AuthorORCID
Thompson, Susan E.0000-0001-7106-4683
Howell, Steve B.0000-0002-2532-2853
Rowe, Jason F.0000-0002-5904-1865
Additional Information:© 2014 American Astronomical Society. Received 2014 January 6; accepted 2014 February 21; published 2014 April 16. We thank the anonymous referee for his or her very helpful comments, which especially helped to improve the clarity of the paper. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This research has made use of NASA’s Astrophysics Data System. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate.
Funders:
Funding AgencyGrant Number
NASANAS5-26555
NASANNX09AF08G
Subject Keywords:binaries: eclipsing; instrumentation: detectors; planetary systems; planets and satellites: detection; stars: statistics; techniques: photometric
Record Number:CaltechAUTHORS:20140529-075408143
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140529-075408143
Official Citation:Contamination in the Kepler Field. Identification of 685 KOIs as False Positives via Ephemeris Matching Based on Q1-Q12 Data Jeffrey L. Coughlin et al. 2014 The Astronomical Journal 147 119
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45955
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:29 May 2014 16:52
Last Modified:01 Dec 2017 04:28

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