1. An ultrahot Neptune in the Neptune desert
- Author
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Jenkins, JS, Díaz, MR, Kurtovic, NT, Espinoza, N, Vines, JI, Rojas, PAP, Brahm, R, Torres, P, Cortés-Zuleta, P, Soto, MG, Lopez, ED, King, GW, Wheatley, PJ, Winn, JN, Ciardi, DR, Ricker, G, Vanderspek, R, Latham, DW, Seager, S, Jenkins, JM, Beichman, CA, Bieryla, A, Burke, CJ, Christiansen, JL, Henze, CE, Klaus, TC, McCauliff, S, Mori, M, Narita, N, Nishiumi, T, Tamura, M, De Leon, JP, Quinn, SN, Villaseñor, JN, Vezie, M, Lissauer, JJ, Collins, KA, Collins, KI, Isopi, G, Mallia, F, Ercolino, A, Petrovich, C, Jordán, A, Acton, JS, Armstrong, DJ, Bayliss, D, Bouchy, F, Belardi, C, Bryant, EM, Burleigh, MR, Cabrera, J, Casewell, SL, Chaushev, A, Cooke, BF, Eigmüller, P, Erikson, A, Foxell, E, Gänsicke, BT, Gill, S, Gillen, E, Günther, MN, Goad, MR, Hooton, MJ, Jackman, JAG, Louden, T, McCormac, J, Moyano, M, Nielsen, LD, Pollacco, D, Queloz, D, Rauer, H, Raynard, L, Smith, AMS, Tilbrook, RH, Titz-Weider, R, Turner, O, Udry, S, Walker, Watson, CA, West, RG, Palle, E, Ziegler, C, Law, N, and Mann, AW
- Subjects
astro-ph.SR ,13. Climate action ,astro-ph.EP ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics - 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).