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, 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. and Batalha, N. (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): 7. ISSN 0067-0049

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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.

Item Type	Article
Identification Number	10.1088/0067-0049/197/1/7
Additional information	‘In these times, during the rise in the popularity of institutional repositories, the Society does not forbid authors from depositing their work in such repositories. However, the AAS regards the deposit of scholarly work in such repositories to be a decision of the individual scholar, as long as the individual's actions respect the diligence of the journals and their reviewers.’ Original article can be found at : http://iopscience.iop.org/ Copyright American Astronomical Society
Keywords	planetary systems, stars: individual (kepler-18, kic 8644288, 2mass j19521906+4444467), techniques: photometric, techniques: spectroscopic
Date Deposited	15 May 2025 12:17
Last Modified	10 Feb 2026 19:17