An Ultra-Hot Neptune in the Neptune desert
Abstract
About one out of 200 Sun-like stars has a planet with an orbital period shorter than one day: an ultra-short-period planet (Sanchis-ojeda et al. 2014; Winn et al. 2018). All of the previously known ultra-short-period planets are either hot Jupiters, with sizes above 10 Earth radii (Re), or apparently rocky planets smaller than 2 Re. Such lack of planets of intermediate size (the "hot Neptune desert") has been interpreted as the inability of low-mass planets to retain any hydrogen/helium (H/He) envelope in the face of strong stellar irradiation. Here, we report the discovery of an ultra-short-period planet with a radius of 4.6 Re and a mass of 29 Me, firmly in the hot Neptune desert. Data from the Transiting Exoplanet Survey Satellite (Ricker et al. 2015) revealed transits of the bright Sun-like star \starname\, every 0.79 days. The planet's mean density is similar to that of Neptune, and according to thermal evolution models, it has a H/He-rich envelope constituting 9.0^(+2.7)_(-2.9)% of the total mass. With an equilibrium temperature around 2000 K, it is unclear how this "ultra-hot Neptune" managed to retain such an envelope. Follow-up observations of the planet's atmosphere to better understand its origin and physical nature will be facilitated by the star's brightness (Vmag=9.8).
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Cite
@article{arxiv.2009.12832,
title = {An Ultra-Hot Neptune in the Neptune desert},
author = {James S. Jenkins and Matías R. Díaz and Nicolás T. Kurtovic and Néstor Espinoza and Jose I. Vines and Pablo A. Peña Rojas and Rafael Brahm and Pascal Torres and Pía Cortés-Zuleta and Maritza G. Soto and Eric D. Lopez and George W. King and Peter J. Wheatley and Joshua N. Winn and David R. Ciardi and George Ricker and Roland Vanderspek and David W. Latham and Sara Seager and Jon M. Jenkins and Charles A. Beichman and Allyson Bieryla and Christopher J. Burke and Jessie L. Christiansen and Christopher E. Henze and Todd C. Klaus and Sean McCauliff and Mayuko Mori and Norio Narita and Taku Nishiumi and Motohide Tamura and Jerome Pitogo de Leon and Samuel N. Quinn and Jesus Noel Villaseñor and Michael Vezie and Jack J. Lissauer and Karen A. Collins and Kevin I. Collins and Giovanni Isopi and Franco Mallia and Andrea Ercolino and Cristobal Petrovich and Andrés Jordán and Jack S. Acton and David J. Armstrong and Daniel Bayliss and François Bouchy and Claudia Belardi and Edward M. Bryant and Matthew R. Burleigh and Juan Cabrera and Sarah L. Casewell and Alexander Chaushev and Benjamin F. Cooke and Philipp Eigmüller and Anders Erikson and Emma Foxell and Boris T. Gänsicke and Samuel Gill and Edward Gillen and Maximilian N. Günther and Michael R. Goad and Matthew J. Hooton and James A. G. Jackman and Tom Louden and James McCormac and Maximiliano Moyano and Louise D. Nielsen and Don Pollacco and Didier Queloz and Heike Rauer and Liam Raynard and Alexis M. S. Smith and Rosanna H. Tilbrook and Ruth Titz-Weider and Oliver Turner and Stéphane Udry and Simon. R. Walker and Christopher A. Watson and Richard G. West and Enric Palle and Carl Ziegler and Nicholas Law and Andrew W. Mann},
journal= {arXiv preprint arXiv:2009.12832},
year = {2020}
}
Comments
26 pages, 10 figures, 3 tables. Published in Nature Astronomy (21/09/2020)