NGTS-13b: a hot 4.8 Jupiter-mass planet transiting a subgiant star
Jordán, Andrés; Wheatley, Peter J.; Bayliss, Daniel; Moyano, Maximiliano; Günther, Maximilian N.; Henderson, Beth A.; Casewell, Sarah L.; Gill, Samuel; Goad, Michael R.; Alves, Douglas R.; Anderson, David R.; Burleigh, Matthew R.; Gillen, Edward; Jenkins, James S.; Lendl, Monika; McCormac, James; Vines, Jose I.; West, Richard G.; Smith, Alexis M. S.; Bryant, Edward M.; Queloz, Didier; Bouchy, François; Chaushev, Alexander; Nielsen, Louise D.; Raynard, Liam; Segransan, Damien; Grieves, Nolan; Udry, Stephane; Acton, Jack S.; Tilbrook, Rosanna H.; Cooke, Benjamin F.; Seidel, Julia V.; Hogan, Aleisha; Eigmueller, Philipp
Switzerland, Chile, United Kingdom, Germany, United States
Abstract
We report the discovery of the massive hot Jupiter NGTS-13b by the Next Generation Transit Survey (NGTS). The V = 12.7 host star is likely in the subgiant evolutionary phase with logg* = 4.04 ± 0.05, Teff = 5819 ± 73 K, M* = 1.30−0.18+0.11 M⊙, and R* = 1.79 ± 0.06 R⊙. The NGTS detected a transiting planet with a period of P = 4.12 days around the star, which was later validated with the Transiting Exoplanet Survey Satellite (TESS; TIC 454069765). We confirm the planet using radial velocities from the CORALIE spectrograph. Using NGTS and TESS full-frame image photometry combined with CORALIE radial velocities, we determine NGTS-13b to have a radius of RP = 1.142 ± 0.046 RJup, a mass of MP = 4.84 ± 0.44 MJup, and an eccentricity of e = 0.086 ± 0.034. Previous studies have suggested that ~4 MJup may be the border separating two formation scenarios (e.g., core accretion and disk instability) and that massive giant planets share similar formation mechanisms as lower-mass brown dwarfs. NGTS-13b is just above 4 MJup, making it an important addition to the statistical sample needed to understand the differences between various classes of substellar companions. The high metallicity of NGTS-13, [Fe/H] = 0.25 ± 0.17, does not support previous suggestions that massive giants are found preferentially around lower metallicity host stars, but NGTS-13b does support findings that more massive and evolved hosts may have a higher occurrence of close-in massive planets than lower-mass unevolved stars.
NGTS and TESS reduced photometry files are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/647/A180