@article{f3c1cc205bd542439a3aa582747a5b31,
title = "Two long-period transiting exoplanets on eccentric orbits: NGTS-20 b (TOI-5152 b) and TOI-5153 b",
abstract = "Context. Long-period transiting planets provide the opportunity to better understand the formation and evolution of planetary systems. Their atmospheric properties remain largely unaltered by tidal or radiative effects of the host star, and their orbital arrangement reflects a different and less extreme migrational history compared to close-in objects. The sample of long-period exoplanets with well-determined masses and radii is still limited, but a growing number of long-period objects reveal themselves in the Transiting Exoplanet Survey Satellite (TESS) data. Aims. Our goal is to vet and confirm single-transit planet candidates detected in the TESS space-based photometric data through spectroscopic and photometric follow-up observations with ground-based instruments. Methods. We used high-resolution spectrographs to confirm the planetary nature of the transiting candidates and measure their masses. We also used the Next Generation Transit Survey (NGTS) to photometrically monitor the candidates in order to observe additional transits. Using a joint modeling of the light curves and radial velocities, we computed the orbital parameters of the system and were able to precisely measure the mass and radius of the transiting planets. Results. We report the discovery of two massive, warm Jupiter-size planets, one orbiting the F8-type star TOI-5153 and the other orbiting the G1-type star NGTS-20 (=TOI-5152). From our spectroscopic analysis, both stars are metal rich with a metallicity of 0.12 and 0.15, respectively. Only TOI-5153 presents a second transit in the TESS extended mission data, but NGTS observed NGTS-20 as part of its mono-transit follow-up program and detected two additional transits. Follow-up high-resolution spectroscopic observations were carried out with CORALIE, CHIRON, FEROS, and HARPS. TOI-5153 hosts a planet with a period of 20.33 days, a planetary mass of 3.26-0.17+0.18 Jupiter masses (MJ), a radius of 1.06-0.04+0.04 RJ, and an orbital eccentricity of 0.091-0.026+0.024. NGTS-20 b is a 2.98-0.15+0.16 MJ planet with a radius of 1.07-0.04+0.04 RJ on an eccentric 0.432-0.023+0.023 orbit with an orbital period of 54.19 days. Both planets are metal enriched and their heavy element content is in line with the previously reported mass-metallicity relation for gas giants. Conclusions. Both warm Jupiters orbit moderately bright host stars, making these objects valuable targets for follow-up studies of the planetary atmosphere and measurement of the spin-orbit angle of the system.",
keywords = "Methods: data analysis, Planetary systems, Planets and satellites: detection, Planets and satellites: gaseous planets, Planets and satellites: individual: NGTS 20/TOI-5152, Planets and satellites: individual: TOI-5153",
author = "S. Ulmer-Moll and M. Lendl and S. Gill and S. Villanueva and Hobson, {M. J.} and F. Bouchy and R. Brahm and D. Dragomir and N. Grieves and C. Mordasini and Anderson, {D. R.} and Acton, {J. S.} and D. Bayliss and A. Bieryla and Burleigh, {M. R.} and Casewell, {S. L.} and G. Chaverot and P. Eigm{\"u}ller and D. Feliz and Gaudi, {B. S.} and E. Gillen and Goad, {M. R.} and Gupta, {A. F.} and G{\"u}nther, {M. N.} and Henderson, {B. A.} and T. Henning and Jenkins, {J. S.} and M. Jones and A. Jord{\'a}n and A. Kendall and Latham, {D. W.} and I. Mireles and M. Moyano and J. Nadol and Osborn, {H. P.} and J. Pepper and Pinto, {M. T.} and A. Psaridi and D. Queloz and S. Quinn and F. Rojas and P. Sarkis and M. Schlecker and Tilbrook, {R. H.} and P. Torres and T. Trifonov and S. Udry and Vines, {J. I.} and R. West and P. Wheatley and X. Yao and Y. Zhao and G. Zhou",
note = "Funding Information: This work has been carried out within the framework of the National Centre of Competence in Research PlanetS supported by the Swiss National Science Foundation under grants 51NF40_182901 and 51NF40_205606. The authors acknowledge the financial support of the SNSF. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2194576. The NGTS facility is operated by the consortium institutes with support from the UK Science and Technology Facilities Council (STFC) under projects ST/M001962/1 and ST/S002642/1. The contributions at the University of Warwick by P.J.W., R.G.W., D.R.A., and S.G. have been supported by STFC through consolidated grants ST/L000733/1 and ST/P000495/1. R.B. acknowledges support from FONDECYT Project 11200751 and from ANID - Millennium Science Initiative. D.D. acknowledges support from the TESS Guest Investigator Program grants 80NSSC21K0108 and 80NSSC22K0185, and NASA Exoplanet Research Program grant 18-2XRP18_2-0136. Some of the observations in this paper made use of the NN-EXPLORE Exoplanet and Stellar Speckle Imager (NESSI). NESSI was funded by the NASA Exoplanet Exploration Program and the NASA Ames Research Center. NESSI was built at the Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. G.Z. thanks the support of the ARC DECRA program DE210101893. A.J., F.R., and P.T. acknowledge support from ANID – Millennium Science Initiative – ICN12_009 and from FONDECYT project 1210718. The results reported herein benefited from collaborations and/or information exchange within the program “Alien Earths” (supported by the National Aeronautics and Space Administration under agreement no. 80NSSC21K0593) for NASA{\textquoteright}s Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA s Science Mission Directorate. J.S.J. gratefully acknowledges support by FONDECYT grant 1201371 and from the ANID BASAL projects ACE210002 and FB210003. M.N.G. acknowledges support from the European Space Agency (ESA) as an ESA Research Fellow. The work performed by HPO has been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation. E.G. gratefully acknowledges support from the David and Claudia Harding Foundation in the form of a Winton Exoplanet Fellowship. T.T. acknowledges support by the DFG Research Unit FOR 2544 “Blue Planets around Red Stars” project no. KU 3625/2-1. T.T. further acknowledges support by the BNSF program “VIHREN-2021” project No. K∏-06-,Z];B/5. J.I.V. acknowledges support of CONICYT-PFCHA/Doctorado Nacional-21191829. The authors acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Centre. This paper includes data collected with the TESS mission obtained from the MAST data archive at the Space Telescope Science Institute (STScI). Funding for the TESS mission is provided by the NASA Explorer program. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This work made use of tpfplotter by J. Lillo-Box (publicly available in www.github.com/jlillo/tpfplotter ), which also made use of the python packages astropy, lightkurve, matplotlib and numpy. This publication makes use of The Data & Analysis Center for Exoplanets (DACE), which is a facility based at the University of Geneva (CH) dedicated to extra-solar planets data visualisation, exchange and analysis. DACE is a platform of the Swiss National Centre of Competence in Research (NCCR) PlanetS, federating the Swiss expertise in Exoplanet research. The DACE platform is available at https://dace.unige.ch . Publisher Copyright: {\textcopyright} ",
year = "2022",
month = oct,
day = "1",
doi = "10.1051/0004-6361/202243583",
language = "English",
volume = "666",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
}