Exoplanetology: Exoplanets & Exomoons

TESS Hunt for Young and Maturing Exoplanets (THYME) X: a two-planet system in the 210 Myr MELANGE-5 Association

By Keith Cowing

Status Report

astro-ph.EP

June 12, 2024

Filed under astro-ph.EP, Crius 221, exoplanet, gyrochronology, MELANGE-5, TESS, TESS Objects of Interest, Theia 424/Volans-Carina, TOI-1224, TOI-1224 b, TOI-1224 c

TESS Hunt for Young and Maturing Exoplanets (THYME) X: a two-planet system in the 210 Myr MELANGE-5 Association — Rotation periods of MELANGE-5 compared to rotation periods of benchmark open clusters. MELANGE-5 members are represented by red stars and the shade indicates the quality of the rotation, with darker red (0) representing a clearly observed rotation in the light curve and lighter red (1) representing a questionable period. MELANGE-5 falls above the 120 Myr clusters, and slightly below the 300 Myr clusters. The gray lines are the “mean” empirical isochrones fitted by Bouma et al. (2023) with ascending time intervals of 100 Myr, 200 Myr, and so on. The astrophysical scatter about these mean lines sets the empirical precision limit for this age-dating method. — astro-ph.EP

Young (<500 Myr) planets are critical to studying how planets form and evolve. Among these young planetary systems, multi-planet 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 the planets are 2.10±0.09R_⊕ and 2.88±0.10R_⊕ and orbit their host star every 4.18 and 17.95 days, respectively. With their bright (K=9.1 mag), small (R_∗=0.44R_⊙), and cool (T_eff =3326K) host star, these planets represent excellent candidates for atmospheric characterization with JWST.

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

Comments: Accepted for publication in The Astronomical Journal; 33 pages, 17 figures, 9 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2406.05234 [astro-ph.EP] (or arXiv:2406.05234v1 [astro-ph.EP] for this version)
Submission history
From: Pa Chia Thao
[v1] Fri, 7 Jun 2024 19:49:49 UTC (2,537 KB)
https://arxiv.org/abs/2406.05234
Astrobiology

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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