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

• Published in: The Astrophysical journal. Supplement series Vol. 197; no. 1; pp. 7 - jQuery1323919489348='48'
• Main 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 III, Thomas N, 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
• Format: Journal Article
• Language: English
• Published: United States IOP Publishing 01.11.2011
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DENSITY; DETECTION; DIAGRAMS; ELECTROMAGNETIC RADIATION; INFORMATION; Iron; NEPTUNE PLANET; Orbitals; PHOTOMETRY; PHYSICAL PROPERTIES; PLANETS; RADIAL VELOCITY; RADIATIONS; SATELLITES; STARS; TESTING; Transit; VALIDATION; VELOCITY; VISIBLE RADIATION
• ISSN: 0067-0049; 1538-4365
• DOI: 10.1088/0067-0049/197/1/7

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 {circled plus}, a radius of 2.00 ? 0.10 R {circled plus}, 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 {circled plus}, a radius of 5.49 ? 0.26 R {circled plus}, and a mean density of 0.59 ? 0.07 g cm3, while Kepler-18d has a mass of 16.4 ? 1.4 M {circled plus}, a radius of 6.98 ? 0.33 R {circled plus} 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.