Exoplanetology: Exoplanets & Exomoons

Discovery and Characterization of a Dense sub-Saturn TOI-6651b

By Keith Cowing
Status Report
astro-ph.EP
September 5, 2024
Filed under , , , , , , , , ,
Discovery and Characterization of a Dense sub-Saturn TOI-6651b
Target pixel file for TOI-6651 in sector 17 (on the left) and sector 57 (on the right) generated with tpfplotter (Aller et al. 2020). The squared region is the aperture mask used in the photometry, whereas the size of the individual red dot is the magnitude contrast (∆m) from TOI6651. The position of TOI-6651 is marked with “1”. — astro-ph.EP

We report the discovery and characterization of a transiting sub-Saturn exoplanet TOI-6651b using PARAS-2 spectroscopic observations. The host, TOI-6651 (mV≈10.2), is a sub-giant, metal-rich G-type star with [Fe/H]=0.225+0.044−0.045, Teff=5940±110 K, and logg=4.087+0.035−0.032.

Joint fitting of the radial velocities from PARAS-2 spectrograph and transit photometric data from Transiting Exoplanet Survey Satellite (TESS) reveals a planetary mass of 61.0+7.6−7.9 M⊕ and radius of 5.09+0.27−0.26 R⊕, in a 5.056973+0.000016−0.000018 day orbit with an eccentricity of 0.091+0.096−0.062.

TOI-6651b has a bulk density of 2.52+0.52−0.44 g cm−3, positioning it among the select few known dense sub-Saturns and making it notably the densest detected with TESS. TOI-6651b is consistent with the positive correlation between planet mass and the host star’s metallicity.

We find that a considerable portion ≈ 87% of the planet’s mass consists of dense materials such as rock and iron in the core, while the remaining mass comprises a low-density envelope of H/He. TOI-6651b lies at the edge of the Neptunian desert, which will be crucial for understanding the factors shaping the desert boundaries.

The existence of TOI-6651b challenges conventional planet formation theories and could be a result of merging events or significant atmospheric mass loss through tidal heating, highlighting the complex interplay of dynamical processes and atmospheric evolution in the formation of massive dense sub-Saturns.

Sanjay Baliwal, Rishikesh Sharma, Abhijit Chakraborty, Akanksha Khandelwal, K.J. Nikitha, Boris S. Safonov, Ivan A. Strakhov, Marco Montalto, Jason D. Eastman, David W. Latham, Allyson Bieryla, Neelam J.S.S.V. Prasad, Kapil K. Bharadwaj, Kevikumar A. Lad, Shubhendra N. Das, Ashirbad Nayak

Comments: 15 pages, 12 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2408.17179 [astro-ph.EP] (or arXiv:2408.17179v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2408.17179
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Related DOI:
https://doi.org/10.1051/0004-6361/202450934
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Submission history
From: Akanksha Khandelwal
[v1] Fri, 30 Aug 2024 10:27:49 UTC (2,949 KB)
https://arxiv.org/abs/2408.17179

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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