TESS Hunt for Young and Maturing Exoplanets (THYME). X. A Two-planet System in the 210 Myr MELANGE-5 Association

Thao, Pa Chia; Mann, Andrew W.; Barber, Madyson G.; Kraus, Adam L.; Tofflemire, Benjamin M.; Bush, Jonathan L.; Wood, Mackenna L.; Collins, Karen A.; Vanderburg, Andrew; Quinn, Samuel N.; Zhou, George; Newton, Elisabeth R.; Ziegler, Carl; Law, Nicholas; Barkaoui, Khalid; Pozuelos, Francisco J.; Timmermans, Mathilde; Gillon, Michaël; Jehin, Emmanuël; Schwarz, Richard P.; Gan, Tianjun; Shporer, Avi; Horne, Keith; Sefako, Ramotholo; Suarez, Olga; Mekarnia, Djamel; Guillot, Tristan; Abe, Lyu; Triaud, Amaury H. M. J.; Radford, Don J.; Lopez Murillo, Ana Isabel; Ricker, George R.; Winn, Joshua N.; Jenkins, Jon M.; Bouma, Luke G.; Fausnaugh, Michael; Guerrero, Natalia M.; Kunimoto, Michelle
Bibliographical reference

The Astronomical Journal

Advertised on:
7
2024
Number of authors
38
IAC number of authors
1
Refereed citations
0
Description
Young (<500 Myr) planets are critical to studying how planets form and evolve. Among these young planetary systems, multiplanet configurations are particularly useful, as they provide a means to control for variables within a system. Here, we report the discovery and characterization of a young planetary system, TOI-1224. We show that the planet host resides within a young population we denote as MELANGE-5. By employing a range of age-dating methods—isochrone fitting, lithium abundance analysis, gyrochronology, and Gaia excess variability—we estimate the age of MELANGE-5 to be 210 ± 27 Myr. MELANGE-5 is situated in close proximity to previously identified younger (80–110 Myr) associations, Crius 221 and Theia 424/Volans-Carina, motivating further work to map out the group boundaries. In addition to a planet candidate detected by the TESS pipeline and alerted as a TESS object of interest, TOI-1224 b, we identify a second planet, TOI-1224 c, using custom search tools optimized for young stars (Notch and LOCoR). We find that the planets are 2.10 ± 0.09 R ⊕ and 2.88 ± 0.10 R ⊕ and orbit their host star every 4.18 and 17.95 days, respectively. With their bright (K = 9.1 mag), small (R * = 0.44 R ⊙), and cool (T eff = 3326 K) host star, these planets represent excellent candidates for atmospheric characterization with JWST.