Detection and characterization of an ultra-dense sub-Neptune planet orbiting the Sun-like star HD 119130

Abstract

We present the discovery and characterization of a new transiting planet from Campaign 17 of the Kepler extended mission K2. HD 119130 b is a warm sub-Neptune on a 17-d orbit around a bright (V = 9.9 mag) solar-like G3 V star with a mass and radius of $M_{\star }=1.00\pm 0.03{\mathrm{M}}_{\odot }$ and $R_{\star }=1.09\pm 0.03{\mathrm{R}}_{\odot }$, respectively. We model simultaneously the K2 photometry and CARMENES spectroscopic data and derive a radius of $R_{\mathrm{p}}=2.63_{-0.10}^{+0.12}{\mathrm{R}}_{\oplus }$ and mass of $M_{\mathrm{p}}=24.5_{-4.4}^{+4.4}{\mathrm{M}}_{\oplus }$, yielding a mean density of $\ddot{I}{}_{\mathrm{p}}=7.4_{-1.5}^{+1.6}\mathrm{g}\mathrm{c}{\mathrm{m}}^{-3}$, which makes it one of the densest sub-Neptune planets known to date. We also detect a linear trend in radial velocities of HD 119130 (${\dot{\hat{I}}}_{\mathrm{RV}}^3=-0.40_{-0.07}^{+0.07}\mathrm{m}{\mathrm{s}}^{-1}{\mathrm{d}}^{-1}$) that suggests a long-period companion with a minimum mass on the order of $33{\mathrm{M}}_{\oplus }$. If confirmed, it would support a formation scenario of HD 119130 b by migration caused by Kozai-Lidov oscillations.

Submitted to A&A; 9 pages, 8 figures, 4 tables