A Dark, Bare Rock For TOI-1685 b From A JWST NIRSpec G395H Phase Curve
We report JWST NIRSpec/G395H observations of TOI-1685 b, a hot rocky super-Earth orbiting an M2.5V star, during a full orbit.
We obtain transmission and emission spectra of the planet and characterize the properties of the phase curve, including its amplitude and offset. The transmission spectrum rules out clear H2-dominated atmospheres, while secondary atmospheres (made of water, methane, or carbon dioxide) cannot be statistically distinguished from a flat line.
The emission spectrum is featureless and consistent with a blackbody-like brightness temperature, helping rule out thick atmospheres with high mean molecular weight. Collecting all evidence, the properties of TOI-1685 b are consistent with a blackbody with no heat redistribution and a low albedo, with a dayside brightness temperature 0.98±0.07 times that of a perfect blackbody in the NIRSpec NRS2 wavelength range (3.823-5.172 um). Our results add to the growing number of seemingly airless M-star rocky planets, thus constraining the location of the “Cosmic Shoreline”.
Three independent data reductions have been carried out, all showing a high-amplitude correlated noise component in the white and spectroscopic light curves. The correlated noise properties are different between the NRS1 and NRS2 detectors – importantly the timescales of the strongest components (4.5 hours and 2.5 hours, respectively) – suggesting the noise is from instrumental rather than astrophysical origins.
We encourage the community to look into the systematics of NIRSpec for long time-series observations.
Rafael Luque, Brandon Park Coy, Qiao Xue, Adina D. Feinstein, Eva-Maria Ahrer, Quentin Changeat, Michael Zhang, Sarah E. Moran, Jacob L. Bean, Edwin Kite, Megan Weiner Mansfield, Enric Pallé
Comments: 26 pages, 19 figures, 8 tables. Submitted to AAS Journals
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2412.03411 [astro-ph.EP] (or arXiv:2412.03411v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2412.03411
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Submission history
From: Rafael Luque
[v1] Wed, 4 Dec 2024 15:49:15 UTC (24,807 KB)
https://arxiv.org/abs/2412.03411
astrobiology
