Exoplanetology: Exoplanets & Exomoons

Hints Of A Sulfur-rich Atmosphere Around the 1.6 R⊕ Super-Earth L98-59 d from JWST NIRSpec G395H Transmission Spectroscopy

By Keith Cowing
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astro-ph.EP
August 30, 2024
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Hints Of A Sulfur-rich Atmosphere Around the 1.6 R⊕ Super-Earth L98-59 d from JWST NIRSpec G395H Transmission Spectroscopy
Transmission spectra of L98-59 d obtained using transitspectroscopy (pink) and FIREFLy (blue) pipelines. The spectral light curves from the two indepedent reductions were fitted using juliet with a similar parametrization at pixel resolution and then binned to R ∼ 100. The residuals between the two reductions show a global offset between the two reductions for the NRS2 detector. — astro-ph.EP

Detecting atmospheres around planets with a radius below 1.6 R⊕, commonly referred to as rocky planets (Rogers_2015, Rogers_2021), has proven to be challenging. However, rocky planets orbiting M-dwarfs are ideal candidates due to their favorable planet-to-star radius ratio. Here, we present one transit observation of the Super-Earth L98-59d (1.58 R⊕, 2.31 M⊕), at the limit of rocky/gas-rich, using the JWST NIRSpec G395H mode covering the 2.8 to 5.1 microns wavelength range.

The extracted transit spectrum from a single transit observation deviates from a flat line by 2.6 to 5.6σ, depending on the data reduction and retrieval setup. The hints of an atmospheric detection are driven by a large absorption feature between 3.3 to 4.8 microns.

A stellar contamination retrieval analysis rejected the source of this feature as being due to stellar inhomogeneities, making the best fit an atmospheric model including sulfur-bearing species, suggesting that the atmosphere of L98-59d may not be at equilibrium.

This result will need to be confirmed by the analysis of the second NIRSpec G395H visit in addition to the NIRISS SOSS transit observation.

Amélie Gressier, Néstor Espinoza, Natalie H. Allen, David K. Sing, Agnibha Banerjee, Joanna K. Barstow, Jeff A. Valenti, Nikole K. Lewis, Stephan M. Birkmann, Ryan C. Challener, Elena Manjavacas, Catarina Alves de Oliveira, Nicolas Crouzet, Tracy. L Beck

Comments: Accepted for publication in the Astrophysical Journal Letters (ApJL), August 25, 2024
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2408.15855 [astro-ph.EP] (or arXiv:2408.15855v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2408.15855
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Related DOI:
https://doi.org/10.3847/2041-8213/ad73d1
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Submission history
From: Amélie Gressier
[v1] Wed, 28 Aug 2024 15:16:48 UTC (4,868 KB)
https://arxiv.org/abs/2408.15855

Astrobiology, Astrochemistry,

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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