Bibcode
Hori, Yasunori; Fukui, Akihiko; Hirano, Teruyuki; Narita, Norio; de Leon, Jerome P.; Ishikawa, Hiroyuki Tako; Hartman, Joel D.; Morello, Giuseppe; Abreu García, Nestor; Álvarez Hernández, Leticia; Béjar, Víctor J. S.; Calatayud-Borras, Yéssica; Carleo, Ilaria; Enoc, Gareb; Esparza-Borges, Emma; Fukuda, Izuru; Galán, Daniel; Geraldía-González, Samuel; Hayashi, Yuya; Ikoma, Masahiro; Ikuta, Kai; Isogai, Keisuke; Kagetani, Taiki; Kawai, Yugo; Kawauchi, Kiyoe; Kimura, Tadahiro; Kodama, Takanori; Korth, Judith; Kusakabe, Nobuhiko; Laza-Ramos, Andrés; Livingston, John H.; Luque, Rafael; Miyakawa, Kohei; Mori, Mayuko; Murgas, Felipe; Orell-Miquel, Jaume; Palle, Enric; Parviainen, Hannu; Peláez-Torres, Alberto; Puig-Subirà, Marta; Sánchez-Benavente, Manuel; Sosa-Guillén, Paula; Stangret, Monika; Terada, Yuka; Muñoz Torres, Sara; Watanabe, Noriharu; Bakos, Gaspar Á.; Barkaoui, Khalid; Beichman, Charles; Benkhaldoun, Zouhair; Boyle, Andrew W.; Ciardi, David R.; Clark, Catherine A.; Collins, Karen A.; Collins, Kevin I.; Conti, Dennis M.; Crossfield, Ian J. M.; Everett, Mark E.; Furlan, Elise; Ghachoui, Mourad; Gillon, Michaël; Gonzales, Erica J.; Higuera, Jesus; Horne, Keith; Howell, Steve B.; Jehin, Emmanuël; Lester, Kathryn V.; Lund, Michael B.; Matson, Rachel; Matthews, Elisabeth C.; Pozuelos, Francisco J.; Safonov, Boris S.; Schlieder, Joshua E.; Schwarz, Richard P.; Sefako, Ramotholo; Srdoc, Gregor; Strakhov, Ivan A.; Timmermans, Mathilde; Waalkes, William C.; Ziegler, Carl; Charbonneau, David; Essack, Zahra; Guerrero, Natalia M.; Harakawa, Hiroki; Hedges, Christina; Ishizuka, Masato; Jenkins, Jon M.; Konishi, Mihoko; Kotani, Takayuki; Kudo, Tomoyuki; Kurokawa, Takashi; Kuzuhara, Masayuki; Nishikawa, Jun; Omiya, Masashi; Ricker, George R.; Seager, Sara; Serizawa, Takuma; Striegel, Stephanie; Tamura, Motohide; Ueda, Akitoshi et al.
Bibliographical reference
The Astronomical Journal
Advertised on:
6
2024
Citations
0
Refereed citations
0
Description
Sub-Neptunes with radii of 2–3 R ⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of close-in small planets. In this paper, we present the discovery and follow-up of four sub-Neptunes orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, and TOI-2406), three of which were newly validated by ground-based follow-up observations and statistical analyses. TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b have radii of , , 2.120 ± 0.067 R ⊕, and and orbital periods of P = 8.02, 8.11, 5.80, and 3.08 days, respectively. Doppler monitoring with the Subaru/InfraRed Doppler instrument led to 2σ upper limits on the masses of <19.1 M ⊕, <19.5 M ⊕, <6.8 M ⊕, and <15.6 M ⊕ for TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b, respectively. The mass–radius relationship of these four sub-Neptunes testifies to the existence of volatile material in their interiors. These four sub-Neptunes, which are located above the so-called "radius valley," are likely to retain a significant atmosphere and/or an icy mantle on the core, such as a water world. We find that at least three of the four sub-Neptunes (TOI-782 b, TOI-2120 b, and TOI-2406 b), orbiting M dwarfs older than 1 Gyr, are likely to have eccentricities of e ∼ 0.2–0.3. The fact that tidal circularization of their orbits is not achieved over 1 Gyr suggests inefficient tidal dissipation in their interiors.