We report the discovery of NGTS-11 b (=TOI-1847 b), a transiting Saturn in a 35.46-day orbit around a mid K-type star (Teff=5050 K). We initially identified the system from a single-transit event in a TESS full-frame image light-curve. Following seventy-nine nights of photometric monitoring with an NGTS telescope, we observed a second full transit of NGTS-11 b approximately one year after the TESS single-transit event. The NGTS transit confirmed the parameters of the transit signal and restricted the orbital period to a set of 13 discrete periods. We combined our transit detections with precise radial velocity measurements to determine the true orbital period and measure the mass of the planet. We find NGTS-11 b has a radius of 0.817+0.028-0.032 RJ, a mass of 0.344+0.092-0.073 MJ, and an equilibrium temperature of just 435+34-32 K, making it one of the coolest known transiting gas giants. NGTS-11 b is the first exoplanet to be discovered after being initially identified as a TESS single-transit event, and its discovery highlights the power of intense photometric monitoring in recovering longer-period transiting exoplanets from single-transit events.
@article{arxiv.2005.00006,
title = {NGTS-11 b / TOI-1847 b: A transiting warm Saturn recovered from a TESS single-transit event},
author = {Samuel Gill and Peter J. Wheatley and Benjamin F. Cooke and Andrés Jordán and Louise D. Nielsen and Daniel Bayliss and David R. Anderson and Jose I. Vines and Monika Lendl and Jack S. Acton and David J. Armstrong and François Bouchy and Rafael Brahm and Edward M. Bryant and Matthew R. Burleigh and Sarah L. Casewell and Philipp Eigmüller and Néstor Espinoza and Edward Gillen and Michael R. Goad and Nolan Grieves and Maximilian N. Günther and Thomas Henning and Melissa J. Hobson and Aleisha Hogan and James S. Jenkins and James McCormac and Maximiliano Moyano and Hugh P. Osborn and Don Pollacco and Didier Queloz and Heike Rauer and Felipe Rojas and Paula Sarkis and Alexis M. S. Smith and Marcelo Tala Pinto and Rosanna H. Tilbrook and Stéphane Udry and Christopher A. Watson and Richard G. West},
journal= {arXiv preprint arXiv:2005.00006},
year = {2020}
}
Comments
8 pages, 3 Figures, 1 table. Accepted to ApJ letters