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

## TL;DR

This paper reports the discovery and detailed characterization of a dense sub-Neptune exoplanet orbiting a Sun-like star, including its mass, radius, density, and potential long-period companion, providing insights into its formation.

## Contribution

First detailed characterization of a dense sub-Neptune with evidence of a possible long-period companion influencing its orbit.

## Key findings

- HD 119130 b is a dense sub-Neptune with a radius of 2.63 R_⊕ and mass of 24.5 M_⊕.
- The planet has a high density of 7.4 g/cm³, making it one of the densest known sub-Neptunes.
- Radial velocity data suggest a long-period companion that may have influenced the planet's migration.

## 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 $M_\star = 1.00\pm0.03\,\mathrm{M_\odot}$ and $R_\star = 1.09\pm0.03\,\mathrm{R_\odot}$, 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 $\rho_\mathrm{p} = 7.4_{-1.5}^{+1.6}\,\mathrm{g\,cm^{-3}}$, 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 ($\dot{\gamma}_{\rm RV}= -0.40^{+0.07}_{-0.07}\,\mathrm{m\,s^{-1}\,d^{-1}}$) 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.