Three Small Planets Transiting a Hyades Star
Cochran, William D.; Endl, Michael; Tamura, Motohide; Hirano, Teruyuki; Winn, Joshua N.; Livingston, John H.; Dai, Fei; Gandolfi, Davide; Nowak, Grzegorz; Albrecht, Simon; Barragan, Oscar; Cabrera, Juan; Csizmadia, Szilard; Eigmüller, Philipp; Erikson, Anders; Fridlund, Malcolm; Fukui, Akihiko; Grziwa, Sascha; Guenther, Eike W.; Hatzes, Artie P.; Korth, Judith; Narita, Norio; Nespral, David; Palle, Enric; Pätzold, Martin; Persson, Carina M.; Prieto-Arranz, Jorge; Rauer, Heike; Van Eylen, Vincent; Deeg, Hans J.; Smith, Alexis M. S.; Kawauchi, Kiyoe; Watanabe, Noriharu; Cusano, Felice; Velasco, Sergio; Tanaka, Yusuke
Japan, United States, Italy, Spain, Denmark, Germany, Netherlands, Sweden
Abstract
We present the discovery of three small planets transiting K2-136 (LP 358 348, EPIC 247589423), a late K dwarf in the Hyades. The planets have orbital periods of 7.9757 ± 0.0011, {17.30681}-0.00036+0.00034, and {25.5715}-0.0040+0.0038 {days}, and radii of 1.05 ± 0.16, 3.14 ± 0.36, and {1.55}-0.21+0.24 {R}\oplus , respectively. With an age of 600-800 Myr, these planets are some of the smallest and youngest transiting planets known. Due to the relatively bright (J = 9.1) host star, the planets are compelling targets for future characterization via radial velocity mass measurements and transmission spectroscopy. As the first known star with multiple transiting planets in a cluster, the system should be helpful for testing theories of planet formation and migration.