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
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Author
Cochran, W.D.
MacQueen, P.J.
Endl, M.
Fabrycky, D.C.
Fortney, J.J.
Miller, N.
Torres, G.
Fressin, F.
Désert, J.-M.
Ragozzine, D.
Sasselov, D.
Carter, J.A.
Quinn, S.N.
Latham, D.W.
Holman, M.J.
Charbonneau, D.
Rowe, J.F.
Bryson, S.T.
Howell, S.B.
Borucki, W.J.
Koch, D.G.
Uddin, K.
Tenenbaum, P.
Still, M.
Mullally, F.
Lissauer, J.J.
Kinemuchi, K.
Jenkins, J.M.
Henze, C.E.
Haas, M.R.
Caldwell, D.
Brugamyer, E.J.
Ciardi, D.R.
Steffen, J.H.
Winn, J.N.
Seager, S.
Demory, B.-O.
Welsh, W.F.
Uddin, K.
Tenenbaum, P.
Mullally, F.
Jenkins, J.M.
Caldwell, D.
Still, M.
Kinemuchi, K.
Marcy, G.W.
Knutson, H.
Isaacson, H.
Howard, A.
Lucas, P.W.
Johnson, J.A.
Horch, E.
Gilliland, R.L.
Gautier, T.N.
Ford, E.B.
Fischer, D.A.
Everett, M.
Deming, D.
Buchhave, L.
Brown, T.M.
Batalha, N.
Attention
2299/7197
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 5345K, 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 ± 2.4gcm. 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 0.07gcm , 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 ± 0.03gcm. Kepler-18c and Kepler-18d have orbital periods near a 2:1 mean-motion resonance, leading to large and readily detected TTVs.