부산대학교 도서관

We report the discovery of K2-161b, which was first identified as a planetary candidate from Kepler K2 photometry of Campaign 14, and whose planetary nature and orbital parameters were then confirmed with precision radial velocities. K2-161b is half as massive as Saturn (⁠|${\rm M_P}= 0.179 \pm 0.021 \, {\rm M_{J}}$|⁠), and has a radius of |${\rm R_P}= 0.840 \pm 0.011 \, {\rm R_J}$|⁠, which translates into a bulk density of |${\rm \rho _P}=0.37 \pm 0.05 \, \mathrm{g}\, \mathrm{cm}^{-3}$|⁠. K2-161b transits its slightly evolved G-type host star (⁠|${\rm M}_{\star }= 1.105 \pm 0.019 \, {\rm M}_{\odot }$|⁠, |${\rm R}_{\star }= 1.669 \pm 0.022 \, {\rm R}_{\odot }$|⁠) every 11.633 64 ± 0.000 10 d and presents a significantly eccentric orbit (e  = 0.420 ± 0.034). We estimate a relatively short circularization time-scale of 1.8 Gyr for the planet, but given the advanced age of the system we expect the planet to be engulfed by its evolving host star in ∼1 Gyr before the orbit circularizes. The low density of the planet coupled to the brightness of the host star (J  = 9.4) makes this system one of the best candidates known to date in the super-Neptune regime for atmospheric characterization via transmission spectroscopy, and to further study the transition region between ice and gas giant planets. [ABSTRACT FROM AUTHOR]