Exoplanetology: Exoplanets & Exomoons

A Transiting Multi-planet System In The 61 Million Year Old Association Theia 116

By Keith Cowing
Status Report
astro-ph.EP
July 30, 2024
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A Transiting Multi-planet System In The 61 Million Year Old Association Theia 116
Radius-period distribution of the known young planet population. Planets are colored based on their ages, with darker purples representing the younger systems. TIC 434398831 b and c are denoted by the stars. We plot the distribution of the known exoplanet population in greyscale for reference. Both TIC 434398831 b and c lie above the mature exoplanet distribution. As they continue to evolve, both planets will likely evolve to lie in the Kepler distribution. — astro-ph.EP

Observing and characterizing young planetary systems can aid in unveiling the evolutionary mechanisms that sculpt the mature exoplanet population.

As an all-sky survey, NASA’s Transiting Exoplanet Survey Satellite (TESS) has expanded the known young planet population as it has observed young comoving stellar populations. This work presents the discovery of a multiplanet system orbiting the 61 Myr old G4V star TIC 434398831 (M = 0.99 Msun, R = 0.91 Rsun, Teff = 5638 K, Tmag = 11.31) located in the Theia 116 comoving population.

We estimate the population’s age based on rotation periods measured from the TESS light curves, isochrone fitting, and measurements of lithium equivalent widths in the spectra of Theia 116 members.

The TESS FFI light curves reveal a mini-Neptune (Rb = 3.51 Rearth, Pb = 3.69 days) and super-Neptune (Rc = 5.63 Rearth, Pc = 6.21 days) with an orbital period ratio slightly larger than 5:3. Follow-up observations from CHEOPS and ground-based telescopes confirm the transits of TIC 434398831 b and c, and constrain their transit times.

We explore the potential mass-loss histories of the two planets in order to probe possible initial conditions of the planets immediately after formation.

Sydney Vach, George Zhou, Chelsea X. Huang, Andrew W. Mann, Madyson G. Barber, Allyson Bieryla, David W. Latham, Karen A. Collins, James G. Rogers, Luke G. Bouma, Stephanie T. Douglas, Samuel N. Quinn, Tyler R. Fairnington, Joachim Krüger, Avi Shporer, Kevin I. Collins, Gregor Srdoc, Richard P. Schwarz, Howard M. Relles, Khalid Barkaoui, Kim K. McLeod, Alayna Schneider, Norio Narita, Akihiko Fukui, Ramotholo Sefako, William Fong, Ismael Mireles, Guillermo Torres, George R. Ricker, Sara Seager, Joshua N. Winn

Comments: 14 pages, 13 figures, 5 tables. Submitted to MNRAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2407.19680 [astro-ph.EP] (or arXiv:2407.19680v1 [astro-ph.EP] for this version)
Submission history
From: Sydney Vach
[v1] Mon, 29 Jul 2024 03:52:43 UTC (10,911 KB)
https://arxiv.org/abs/2407.19680
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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