A warm super-Neptune around the G-dwarf star TOI-1710 revealed with TESS, SOPHIE and HARPS-N (2204.08984v2)

Abstract: We report the discovery and characterization of the transiting extrasolar planet TOI-1710$:$b. It was first identified as a promising candidate by the Transiting Exoplanet Survey Satellite (TESS). Its planetary nature was then established with SOPHIE and HARPS-N spectroscopic observations via the radial-velocity method. The stellar parameters for the host star are derived from the spectra and a joint Markov chain Monte-Carlo (MCMC) adjustment of the spectral energy distribution and evolutionary tracks of TOI-1710. A joint MCMC analysis of the TESS light curve and the radial-velocity evolution allows us to determine the planetary system properties. From our analysis, TOI-1710$:$b is found to be a massive warm super-Neptune ($M_{\rm p}=28.3:\pm:4.7:{\rm M}{\rm Earth}$ and $R{\rm p}=5.34:\pm:0.11:{\rm R}{\rm Earth}$) orbiting a G5V dwarf star ($T{\rm eff}=5665\pm~55\mathrm{K}$) on a nearly circular 24.3-day orbit ($e=0.16:\pm:0.08$). The orbital period of this planet is close to the estimated rotation period of its host star $P_{\rm rot}=22.5\pm2.0~\mathrm{days}$ and it has a low Keplerian semi-amplitude $K=6.4\pm1.0~\mathrm{m:s^{-1}}$; we thus performed additional analyses to show the robustness of the retrieved planetary parameters. With a low bulk density of $1.03\pm0.23~\mathrm{g:cm^{-3}}$ and orbiting a bright host star ($J=8.3$, $V=9.6$), TOI-1710$:$b is one of the best targets in this mass-radius range (near the Neptunian desert) for atmospheric characterization via transmission spectroscopy, a key measurement in constraining planet formation and evolutionary models of sub-Jovian planets.