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

November 2011 • 2011ApJS..197....7C

Authors • Cochran, William D. • Fabrycky, Daniel C. • Torres, Guillermo • Fressin, François • Désert, Jean-Michel • Ragozzine, Darin • Sasselov, Dimitar • Fortney, Jonathan J. • Rowe, Jason F. • Brugamyer, Erik J. • Bryson, Stephen T. • Carter, Joshua A. • Ciardi, David R. • Howell, Steve B. • Steffen, Jason H. • Borucki, William. J. • Koch, David G. • Winn, Joshua N. • Welsh, William F. • Uddin, Kamal • Tenenbaum, Peter • Still, M. • Seager, Sara • Quinn, Samuel N. • Mullally, F. • Miller, Neil • Marcy, Geoffrey W. • MacQueen, Phillip J. • Lucas, Phillip • Lissauer, Jack J. • Latham, David W. • Knutson, Heather • Kinemuchi, K. • Johnson, John A. • Jenkins, Jon M. • Isaacson, Howard • Howard, Andrew • Horch, Elliott • Holman, Matthew J. • Henze, Christopher E. • Haas, Michael R. • Gilliland, Ronald L. • Gautier, Thomas N., III • Ford, Eric B. • Fischer, Debra A. • Everett, Mark • Endl, Michael • Demory, Brice-Oliver • Deming, Drake • Charbonneau, David • Caldwell, Douglas • Buchhave, Lars • Brown, Timothy M. • Batalha, Natalie

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 _sun, a radius of 1.1 R _sun, 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 cm³. 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 cm³, 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 cm³. Kepler-18c and Kepler-18d have orbital periods near a 2:1 mean-motion resonance, leading to large and readily detected TTVs.

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.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2011ApJS..197....7C
• PDF https://iopscience.iop.org/article/10.1088/0067-0049/197/1/7/pdf
• PDF https://stacks.iop.org/0067-0049/197/7/pdf
• PREPRINT http://arxiv.org/abs/1110.0820
• DATA http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?type=REFERENCE&bibcode=2011ApJS..197....7C
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2011ApJS..197....7C
• DATA https://irsa.ipac.caltech.edu/bibdata/2011/C/2011ApJS..197....7C.html
• ELECTR https://doi.org/10.1088%2F0067-0049%2F197%2F1%2F7
• SPIRES http://inspirehep.net/search?p=find+eprint+arXiv:1110.0820