K2-99 revisited: a non-inflated warm Jupiter, and a temperate giant planet on a 522-d orbit around a subgiant

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 $R_{\star }=2.55\pm 0.02$ ${\mathrm{R}}_{\odot }$. The new light curve also contains four transits of K2-99b, which we use to improve our knowledge of the planetary properties. We find the planet to be a non-inflated warm Jupiter, with $R_{\mathrm{b}}=1.06\pm 0.01$ ${\mathrm{R}}_{\mathrm{Jup}}$. Sixty new radial velocity measurements from HARPS, HARPS-N, and HIRES enable the determination of the orbital parameters of K2-99c, which were previously poorly constrained. We find that this outer planet has a minimum mass $M_{\mathrm{c}}\sin i_{\mathrm{c}}=8.4\pm 0.2$ ${\mathrm{M}}_{\mathrm{Jup}}$, and an eccentric orbit ($e_{\mathrm{c}}=0.210\pm 0.009$) with a period of $522.2\pm 1.4$ 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.

16 pages, 8 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society

References in corpus (35)

• The Gaia mission
• Modules for Experiments in Stellar Astrophysics (MESA)
• The Transiting Exoplanet Survey Satellite
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• The K2 Mission: Characterization and Early results
• EXOFAST: A fast exoplanetary fitting suite in IDL
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• New Grids of ATLAS9 Model Atmospheres
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• ADIPLS -- the Aarhus adiabatic oscillation package
• Tidal Evolution of Close-in Extra-Solar Planets
• Astrometric exoplanet detection with Gaia
• The CHEOPS mission
• Standing on the shoulders of Dwarfs: the $Kepler$ asteroseismic LEGACY sample I - oscillation mode parameters
• Determining stellar macroturbulence using asteroseismic rotational velocities from Kepler
• EVEREST: Pixel Level Decorrelation of K2 Light curves
• Efficient fitting of multiplanet Keplerian models to radial velocity and astrometry data
• Asteroseismology of solar-type stars
• Obliquities of Kepler Stars: Comparison of Single- and Multiple-Transit Systems
• Impact on asteroseismic analyses of regular gaps in Kepler data
• Large eccentricity, low mutual inclination: the three-dimensional architecture of a hierarchical system of giant planets
• Gap interpolation by inpainting methods : Application to Ground and Space-based Asteroseismic data
• The HARPS search for southern extra-solar planets. XXXI. Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities
• A Class of Warm Jupiters with Mutually Inclined, Apsidally Misaligned, Close Friends
• The Photoeccentric Effect and Proto-Hot Jupiters II. KOI-1474.01, a candidate eccentric planet perturbed by an unseen companion
• Error estimation in astronomy: A guide
• NGTS-11 b / TOI-1847 b: A transiting warm Saturn recovered from a TESS single-transit event
• Determining the true mass of radial-velocity exoplanets with Gaia: 9 planet candidates in the brown-dwarf/stellar regime and 27 confirmed planets
• The stellar obliquity, planet mass, and very low albedo of Qatar-2 from K2 Photometry
• A transit timing variation observed for the long-period extremely low density exoplanet HIP 41378f
• Determining the mass of the planetary candidate HD 114762 b using Gaia
• Influence of magnetic activity on the determination of stellar parameters through asteroseismology
• NGTS-14Ab: a Neptune-sized transiting planet in the desert
• An eclipsing M-dwarf close to the hydrogen burning limit from NGTS
• Evidence for a Non-Dichotomous Solution to the Kepler Dichotomy: Mutual Inclinations of Kepler Planetary Systems from Transit Duration Variations