K2-99 revisited: a non-inflated warm Jupiter, and a temperate giant planet on a 522-d orbit around a subgiant
Fridlund, M.; Guenther, E. W.; García, R. A.; Barragán, O.; Dai, F.; Gandolfi, D.; Korth, J.; Hatzes, A. P.; Smith, A. M. S.; Cabrera, J.; Cochran, W. D.; Palle, E.; Persson, C. M.; Van Eylen, V.; Nowak, G.; Pérez Hernández, F.; Serrano, L. M.; Deeg, H. J.; Goffo, E.; Lam, K. W. F.; Luque, R.; Redfield, S.; Rodler, F.; Mathur, S.; Csizmadia, Sz; Isaacson, H.; Breton, S. N.; Kabath, P.; Howard, A. W.; Livingston, J. H.; Georgieva, I. Y.; Albrecht, S. H.
Germany, France, United States, Italy, Sweden, Spain, Denmark, United Kingdom, Netherlands, Czech Republic, Japan, Chile
Abstract
We report new photometric and spectroscopic observations of the K2-99 planetary system. Asteroseismic analysis of the short-cadence light curve from K2's Campaign 17 allows us to refine the stellar properties. We find K2-99 to be significantly smaller than previously thought, with R⋆ = 2.55 ± 0.02 R⊙. The new light curve also contains four transits of K2-99 b, which we use to improve our knowledge of the planetary properties. We find the planet to be a non-inflated warm Jupiter, with Rb = 1.06 ± 0.01 $\mathrm{R_{\rm Jup}}$. 60 new radial velocity measurements from HARPS, HARPS-N, and HIRES enable the determination of the orbital parameters of K2-99 c, which were previously poorly constrained. We find that this outer planet has a minimum mass Mcsin ic = 8.4 ± 0.2 $\mathrm{M_{\rm Jup}}$, and an eccentric orbit (ec = 0.210 ± 0.009) with a period of 522.2 ± 1.4 d. Upcoming TESS observations in 2022 have a good chance of detecting the transit of this planet, if the mutual inclination between the two planetary orbits is small.