R. Luque, G. Nowak, E. Pallé, F. Dai, A. Kaminski, E. Nagel, D. Hidalgo, F. Bauer, M. Lafarga, J. Livingston, O. Barragán, T. Hirano, M. Fridlund, D. Gandolfi, A. B. Justesen, M. Hjorth, V. Van Eylen, J. N. Winn, M. Esposito, J. C. Morales, S. Albrecht, R. Alonso, P. J. Amado, P. Beck, J. A. Caballero, J. Cabrera, W. D. Cochran, Sz. Csizmadia, H. Deeg, Ph. Eigmüller, M. Endl, A. Erikson, A. Fukui, S. Grziwa, E. W. Guenther, A. P. Hatzes, E. Knudstrup, J. Korth, K. W. F. Lam, M. N. Lund, S. Mathur, P. Montañes-Rodríguez, N. Narita, D. Nespral, P. Niraula, M. Pätzold, C. M. Persson, J. Prieto-Arranz, A. Quirrenbach, H. Rauer, S. Redfield, A. Reiners, I. Ribas and A. M. S. Smith. 2019. Detection and characterization of an ultra-dense sub-Neptunian planet orbiting the Sun-like star K2-292. Astronomy and Astrophysics 623, DOI: 10.1051/0004-6361/201834952
We present the discovery and characterization of a new transiting planet from Campaign 17 of the Kepler extended mission K2. The planet K2-292 b is a warm sub-Neptune on a 17 day orbit around a bright (V = 9.9 mag) solar-like G3 V star with a mass and radius of M-* = 1.00 +/- 0.03 M-circle dot and R-* = 1.09 +/- 0.03 R-circle dot , respectively. We modeled simultaneously the K2 photometry and CARMENES spectroscopic data and derived a radius of R-p = 2.63(-0.10)(+0.12)R(circle plus) and mass of M-p = 24.5(-4.4)(+4.4)M(circle plus), yielding a mean density of rho(p) = 7.4(-1.5)(+1.6)g cm(-3) , which makes it one of the densest sub-Neptunian planets known to date. We also detected a linear trend in the radial velocities of K2-292 (gamma(RV) = -0.40(-0.07)(+0.07) m s(-1) d(-1)) that suggests a long-period companion with a minimum mass on the order of 33 M-circle plus. If confirmed, it would support a formation scenario of K2-292 b by migration caused by Kozai-Lidov oscillations.