Exoplanetology: Exoplanets & Exomoons

Precise Density Measurement of TOI-1430 b, A Young Planet With An Evaporating Atmosphere

By Keith Cowing
Status Report
astro-ph.EP
November 21, 2024
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Precise Density Measurement of TOI-1430 b, A Young Planet With An Evaporating Atmosphere
Detection and vetting of the candidate exoplanet TOI-1430.01. Panel (a) shows the TOI-1430’s stacked light curve and the detrending model (in red). Panel (b) shows the flattened light curve and the position of the odd (magenta) and even (blue) transits. Panels (c) are a comparison between the mean depths of the odd and even transits; the dashed lines are the mean depths while the shaded colored regions represent the 3Οƒ confidence interval. Panel (d) is the TLS periodogram: the period of the peak is indicated with a green triangle. — astro-ph.EP

Small-sized exoplanets in tight orbits around young stars (10-1000 Myr) give us the opportunity to investigate the mechanisms that led to their formation, the evolution of their physical and orbital properties and, especially, of their atmospheres.

Thanks to the all-sky survey carried out by TESS, many of these exoplanets have been discovered and have subsequently been characterized with dedicated follow-up observations. In the context of a collaboration among the GAPS, TKS and CPS teams, we measured with a high level of precision the mass and the radius of TOI-1430 b, a young (~700 Myr) exoplanet with an escaping He atmosphere orbiting the K-dwarf star HD 235088 (TOI-1430).

By adopting appropriate stellar parameters, which were measured in this work, we were able to simultaneously model the signals due to strong stellar activity and the transiting planet TOI-1430 b in both photometric and spectroscopic series. This allowed us to measure the density of the planet with high precision, and reconstruct the evolution of its atmosphere.

TOI-1430 is an active K-dwarf star born 700+/-150 Myr ago and rotates in ~12 d. It hosts a mini-Neptune whose orbital period is Pb=7.434133+/-0.000004 d. Thanks to long-term monitoring of this target performed with TESS, HARPS-N, HIRES, and APF, we estimated a radius Rb=1.98+/-0.07 RβŠ•, a mass Mb=4.2+/-0.8 MβŠ•, and thus a planetary density ρb=0.5+/-0.1 ΟβŠ•. TOI-1430 b is hence a low-density mini-Neptune with an extended atmosphere, at the edge of the radius gap. Because this planet is known to have an evaporating atmosphere of He, we reconstructed its atmospheric history.

Our analysis supports the scenario in which, shortly after its birth, TOI-1430 b may have been super-puffy, with a radius 5x-13x and a mass 1.5x-2x that of today; in ~200 Myr from now, TOI-1430 b should lose its envelope, showing its Earth-size core.

The GAPS Programme At TNG. LXV. Precise Density Measurement of TOI-1430 b, A Young Planet With An Evaporating Atmosphere

D. Nardiello, J. M. Akana Murphy, R. Spinelli, M. Baratella, S. Desidera, V. Nascimbeni, L. Malavolta, K. Biazzo, A. Maggio, D. Locci, S. Benatti, N. M. Batalha, V. D’Orazi, L. Borsato, G. Piotto, R. J. Oelkers, M. Mallonn, A. Sozzetti, L. R. Bedin, G. Mantovan, T. Zingales, L. Affer, A. Bignamini, A. S. Bonomo, L. Cabona, K. A. Collins, M. Damasso, S. Filomeno, A. Ghedina, A. Harutyunyan, A. F. Lanza, L. Mancini, M. Rainer, G. Scandariato, R. P. Schwarz, R. Sefako, G. Srdoc

Comments: 30 pages, 19 figures, 8 tables. Accepted for publication in Astronomy & Astrophysics on 16 November 2024. Electronic material (tables G1-G3) will soon be available on the CDS or upon request to the first author. Abstract shortened
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2411.12795 [astro-ph.EP] (or arXiv:2411.12795v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2411.12795
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Submission history
From: Domenico Nardiello Dr.
[v1] Tue, 19 Nov 2024 19:00:00 UTC (4,622 KB)
https://arxiv.org/abs/2411.12795
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) πŸ––πŸ»