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Kepler-18b,c, and d: A System of Three Planets Confirmed by Transit Timing Variations, Light Curve Validation, Warm-Spitzer Photometry, and Radial Velocity Measurements

Cochran, William D. and Ciardi, David R. and Knutson, Heather and Johnson, John A. and Howard, Andrew W. (2011) Kepler-18b,c, and d: A System of Three Planets Confirmed by Transit Timing Variations, Light Curve Validation, Warm-Spitzer Photometry, and Radial Velocity Measurements. Astrophysical Journal Supplement Series, 197 (1). Art. No. 7. ISSN 0067-0049. https://resolver.caltech.edu/CaltechAUTHORS:20111213-110331493

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Abstract

We report the detection of three transiting planets around a Sun-like star, which we designate Kepler-18. The transit signals were detected in photometric data from the Kepler satellite, and were confirmed to arise from planets using a combination of large transit-timing variations (TTVs), radial velocity variations, Warm-Spitzer observations, and statistical analysis of false-positive probabilities. The Kepler-18 star has a mass of 0.97 M_☉, a radius of 1.1 R_☉, an effective temperature of 5345 K, and an iron abundance of [Fe/H] = +0.19. The planets have orbital periods of approximately 3.5, 7.6, and 14.9 days. The innermost planet "b" is a "super-Earth" with a mass of 6.9 ± 3.4 M_⊕, a radius of 2.00 ± 0.10 R_⊕, and a mean density of 4.9 ± 2.4 g cm^3. The two outer planets "c" and "d" are both low-density Neptune-mass planets. Kepler-18c has a mass of 17.3 ± 1.9 M_⊕, a radius of 5.49 ± 0.26 R_⊕, and a mean density of 0.59 ± 0.07 g cm^3, while Kepler-18d has a mass of 16.4 ± 1.4 M_⊕, a radius of 6.98 ± 0.33 R_⊕ and a mean density of 0.27 ± 0.03 g cm^3. Kepler-18c and Kepler-18d have orbital periods near a 2:1 mean-motion resonance, leading to large and readily detected TTVs.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0067-0049/197/1/7DOIArticle
http://iopscience.iop.org/0067-0049/197/1/7/PublisherArticle
ORCID:
AuthorORCID
Ciardi, David R.0000-0002-5741-3047
Knutson, Heather0000-0002-0822-3095
Howard, Andrew W.0000-0001-8638-0320
Additional Information:© 2011 The American Astronomical Society. Received 2011 July 8; accepted 2011 September 1; published 2011 October 11. Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology. Kepler was competitively selected as the tenth Discovery mission. Funding for the Kepler Mission is provided by NASA’s Science Mission Directorate. We are deeply grateful for the very hard work of the entire Kepler team. This research is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. 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 the National Aeronautics and Space Administration. The Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation.
Group:Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
NASA/JPL/CaltechUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:planetary systems; stars: individual (Kepler-18, KIC 8644288, 2MASS J19521906+4444467); techniques: photometric; techniques: spectroscopic
Issue or Number:1
Record Number:CaltechAUTHORS:20111213-110331493
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20111213-110331493
Official Citation:Kepler-18b, c, and d: A System of Three Planets Confirmed by Transit Timing Variations, Light Curve Validation, Warm-Spitzer Photometry, and Radial Velocity Measurements William D. Cochran et al. 2011 ApJS 197 7
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28445
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:13 Dec 2011 22:49
Last Modified:03 Oct 2019 03:32

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