The proliferation of exoplanet discoveries in exotic environments like the Neptune desert challenges our understanding of planetary atmospheres under intense irradiation. The unexpected discovery of LTT9779 b, an ultra-hot Neptune within this desert, offers a prime opportunity for atmospheric studies.
We build on prior observations of LTT9779 b from TESS, Spitzer, and CHEOPS, incorporating new VLT/ESPRESSO data to probe its atmospheric dynamics. Preliminary analyses suggest a metal-rich atmosphere and a high day-side geometric albedo, possibly indicating silicate clouds. Minimal atmospheric escape is observed, contrasting existing models of planetary evolution under extreme irradiation.
We obtained the transmission spectrum of LTT9779 b between 0.4 and 0.78 microns with ESPRESSO, addressing systematics across three transits. Our analysis focused on the sodium doublet and H-alpha, using cross-correlation with models containing Na, K, FeH, TiO, and VO. No significant atmospheric signal was detected, with metallicity limits set at [Fe/H] >= 2.25 (>= 180 times solar).
The non-detection aligns with a high-metallicity, cloud-free model, implying a high mean molecular weight and reduced atmospheric scale height. We interpret this as evidence for a metal-rich atmosphere with suppressed spectral features, possibly due to high-altitude clouds or hazes. These findings are consistent with JWST observations, supporting the hypothesis of metal-rich atmospheres obscured by aerosols in extreme environments.
R. Ramírez Reyes, James S. Jenkins, Elyar Sedaghati, J. V. Seidel, Yakiv Pavlenko, E. Palle, Mercedes López-Morales, Douglas Alves, José Vines, Pablo A. Peña R, Matías R. Díaz, Patricio Rojo
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2501.17272 [astro-ph.EP] (or arXiv:2501.17272v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2501.17272
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Submission history
From: Ricardo Ramirez Reyes
[v1] Tue, 28 Jan 2025 20:05:19 UTC (7,955 KB)
https://arxiv.org/abs/2501.17272
Astrobiology,
