A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654статья
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Дата последнего поиска статьи во внешних источниках: 20 февраля 2024 г.
Авторы:
Dai Fei,
Schlaufman Kevin C.,
Reggiani Henrique,
Bouma Luke,
Howard Andrew W.,
Chontos Ashley,
Pidhorodetska Daria,
Van Zandt Judah,
Akana Murphy Joseph M.,
Rubenzahl Ryan A.,
Polanski Alex S.,
Lubin Jack,
Beard Corey,
Giacalone Steven,
Holcomb Rae,
Batalha Natalie M.,
Crossfield Ian,
Dressing Courtney,
Fulton Benjamin,
Huber Daniel,
Isaacson Howard,
Kane Stephen R.,
Petigura Erik A.,
Robertson Paul,
Weiss Lauren M.,
Belinski Alexander A.,
Boyle Andrew W.,
Burke Christopher J.,
Castro-González Amadeo,
Ciardi David R.,
Daylan Tansu,
Fukui Akihiko,
Gill Holden,
Guerrero Natalia M.,
Hellier Coel,
Howell Steve B.,
Lillo-Box Jorge,
Murgas Felipe,
Narita Norio,
Pallé Enric,
Rodriguez David R.,
Savel Arjun B.,
Shporer Avi,
Stassun Keivan G.,
Striegel Stephanie,
Caldwell Douglas A.,
Jenkins Jon M.,
Ricker George R.,
Seager Sara,
Vanderspek Roland,
Winn Joshua N.
Аннотация:We report the discovery and Doppler mass measurement of a 7.4 days 2.3 R ⊕ mini-Neptune around a metal-poor K dwarf BD+29 2654 (TOI-2018). Based on a high-resolution Keck/HIRES spectrum, the Gaia parallax, and multiwavelength photometry from the UV to the mid-infrared, we found that the host star has Teff=4174+34−42 K, logg=4.62+0.02−0.03 , [Fe/H] = - 0.58 ± 0.18, M * = 0.57 ± 0.02 M ⊙, and R * = 0.62 ± 0.01 R ⊙. Precise Doppler measurements with Keck/HIRES revealed a planetary mass of M p = 9.2 ± 2.1 M ⊕ for TOI-2018 b. TOI-2018 b has a mass and radius that are consistent with an Earthlike core, with a ~1%-by-mass hydrogen/helium envelope or an ice-rock mixture. The mass of TOI-2018 b is close to the threshold for runaway accretion and hence giant planet formation. Such a threshold is predicted to be around 10M ⊕ or lower for a low-metallicity (low-opacity) environment. If TOI-2018 b is a planetary core that failed to undergo runaway accretion, it may underline the reason why giant planets are rare around low-metallicity host stars (one possibility is their shorter disk lifetimes). With a K-band magnitude of 7.1, TOI-2018 b may be a suitable target for transmission spectroscopy with the James Webb Space Telescope. The system is also amenable to metastable Helium observation; the detection of a Helium exosphere would help distinguish between a H/He-enveloped planet and a water world.