A Massive Hot Jupiter Orbiting a Metal-rich Early M Star Discovered in the TESS Full-frame Images
Latham, David W.; Quinn, Samuel N.; Littlefield, Colin; Stassun, Keivan G.; Howell, Steve B.; Collins, Karen A.; Ricker, George R.; Vanderspek, Roland; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Burgasser, Adam J.; de Leon, Jerome; Barkaoui, Khalid; Dransfield, Georgina; Shporer, Avi; Mireles, Ismael; Fukui, Akihiko; Narita, Norio; Mann, Andrew W.; Rackham, Benjamin V.; Gillon, Michaël; de Wit, Julien; Gan, Tianjun; Sefako, Ramotholo; Doyon, René; Charbonneau, David; Mao, Shude; Furlan, Elise; Vezie, Michael; Wang, Sharon X.; Artigau, Étienne; Cook, Neil J.; Alvarado-Montes, Jaime A.; Timmermans, Mathilde; Cadieux, Charles; Jahandar, Farbod; Vazan, Allona; Lin, D. N. C.; Arnold, Luc; Burdanov, Artem; Hooton, Matthew J.; Lewis, Hannah M.; Ormel, Chris W.
China, Canada, Israel, Australia, United States, Belgium, Spain, Japan, United Kingdom, South Africa
Abstract
Observations and statistical studies have shown that giant planets are rare around M dwarfs compared with Sun-like stars. The formation mechanism of these extreme systems has remained under debate for decades. With the help of the TESS mission and ground-based follow-up observations, we report the discovery of TOI-4201b, the most massive and densest hot Jupiter around an M dwarf known so far with a radius of 1.22 ± 0.04 R J and a mass of 2.48 ± 0.09 M J, about 5 times heavier than most other giant planets around M dwarfs. It also has the highest planet-to-star mass ratio (q ~ 4 × 10-3) among such systems. The host star is an early M dwarf with a mass of 0.61 ± 0.02 M ⊙ and a radius of 0.63 ± 0.02 R ⊙. It has significant supersolar iron abundance ([Fe/H] = 0.52 ± 0.08 dex). However, interior structure modeling suggests that its planet TOI-4201b is metal-poor, which challenges the classical core-accretion correlation of stellar-planet metallicity, unless the planet is inflated by additional energy sources. Building on the detection of this planet, we compare the stellar metallicity distribution of four planetary groups: hot/warm Jupiters around G/M dwarfs. We find that hot/warm Jupiters show a similar metallicity dependence around G-type stars. For M-dwarf host stars, the occurrence of hot Jupiters shows a much stronger correlation with iron abundance, while warm Jupiters display a weaker preference, indicating possible different formation histories.