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TESS Hunt for Young and Maturing Exoplanets (THYME) XII: A Young Mini-Neptune on the Upper Edge of the Radius Valley in the Hyades Cluster

By Keith Cowing
Status Report
astro-ph.EP
October 17, 2024
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TESS Hunt for Young and Maturing Exoplanets (THYME) XII: A Young Mini-Neptune on the Upper Edge of the Radius Valley in the Hyades Cluster
LEFT Panel: Contrast curves obtained from Gemini North ‘Alopeke and Gemini South Zorro instruments. Insets showcase 832 nm reconstructed images, highlighting the increased contrasts achieved with Zorro on Gemini South due to better seeing conditions and a longer total integration time. No close companion star was detected within the achieved 5σ magnitude contrast curves and angular limits from the 8-m diffraction limit out to 1.2 ′′. At the distance of TOI-4364, these limits correspond to spatial separations ranging from 0.88 − 52.8 AU. RIGHT Panel: SOAR sensitivity curve taken on October 18, 2021. The 5σ sensitivity limits are shown out to 3.15′′, corresponding to a projected separation of 138.1 AU. — astro-ph.EP

We present the discovery and characterization of TOI-4364 b, a young mini-Neptune in the tidal tails of the Hyades cluster, identified through TESS transit observations and ground-based follow-up photometry.

The planet orbits a bright M dwarf (K=9.1 mag) at a distance of 44 pc, with an orbital period of 5.42 days and an equilibrium temperature of 488+4−4 K. The host star’s well-constrained age of 710 Myr makes TOI-4364 b an exceptional target for studying early planetary evolution around low-mass stars. We determined a planetary radius of 2.01+0.1−0.08 Earth radii, indicating that this planet is situated near the upper edge of the radius valley. This suggests that the planet retains a modest H/He envelope.

As a result, TOI-4364 b provides a unique opportunity to explore the transition between rocky super-Earths and gas-rich mini-Neptunes at the early stages of evolution. Its radius, which may still evolve as a result of ongoing atmospheric cooling, contraction, and photoevaporation, further enhances its significance for understanding planetary development. Furthermore, TOI-4364 b possesses a moderately high Transmission Spectroscopy Metric of 44.2 positioning it as a viable candidate for atmospheric characterization with instruments such as JWST. This target has the potential to offer crucial insights into atmospheric retention and loss in young planetary systems.

Adam Distler, Melinda Soares-Furtado, Andrew Vanderburg, Jack Schulte, Juliette Becker, Andrew W. Mann, Steve B. Howell, Adam L. Kraus, Khalid Barkaoui, César Briceño, Karen A. Collins, Dennis Conti, Jon M. Jenkins, Mary Anne Limbach, Samuel N. Quinn, Jake D. Turner, Joseph D. Twicken, Richard P. Schwarz, Sara Seager, Joshua N. Winn, Carl Ziegler

Comments: 18 pages, 9 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2410.11990 [astro-ph.EP] (or arXiv:2410.11990v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2410.11990
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Submission history
From: Adam Distler
[v1] Tue, 15 Oct 2024 18:53:40 UTC (2,008 KB)
https://arxiv.org/abs/2410.11990

Astrobiology,

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) 🖖🏻