Discovery and characterization of a dense sub-Saturn TOI-6651b

Autor: Baliwal, Sanjay, Sharma, Rishikesh, Chakraborty, Abhijit, Khandelwal, Akanksha, Nikitha, K. J., Safonov, Boris S., Strakhov, Ivan A., Montalto, Marco, Eastman, Jason D., Latham, David W., Bieryla, Allyson, Prasad, Neelam J. S. S. V., Bharadwaj, Kapil K., Lad, Kevikumar A., Das, Shubhendra N., Nayak, Ashirbad
Rok vydání: 2024
Předmět:
Druh dokumentu: Working Paper
DOI: 10.1051/0004-6361/202450934
Popis: We report the discovery and characterization of a transiting sub-Saturn exoplanet TOI-6651b using PARAS-2 spectroscopic observations. The host, TOI-6651 ($m_{V}\approx 10.2$), is a sub-giant, metal-rich G-type star with $[{\rm Fe/H}] = 0.225^{+0.044}_{-0.045}$, $T_{\rm eff} = 5940\pm110\ \mathrm{K}$, and $\log{g} = 4.087^{+0.035}_{-0.032}$. 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 $61.0^{+7.6}_{-7.9}\ M_\oplus$ and radius of $5.09^{+0.27}_{-0.26}\ R_\oplus$, 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 $2.52^{+0.52}_{-0.44}\ \mathrm{g\ cm^{-3}}$, 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 $\approx$ 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.
Comment: 15 pages, 12 figures
Databáze: arXiv
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