Astronomy & Telescopes

JWST COMPASS: NIRSpec/G395H Transmission Observations of the Super-Earth TOI-776b

By Keith Cowing
Status Report
astro-ph.EP
January 27, 2025
Filed under , , , , , , , ,
JWST COMPASS: NIRSpec/G395H Transmission Observations of the Super-Earth TOI-776b
Allowed parameter space in terms of opaque pressure level (either a cloud top or surface pressure, bar) versus log metallicity for the ExoTiC-JEDI (top, pinks) and Eureka! (middle, blues) reductions for Visits 1 (left) and 2 (right). In all cases, we are able to rule out metallicities of at least 100× solar (i.e., mean molecular weights of ∼5.5) with an opaque pressure of 1 millibar by 3σ. The exact limits of each reduction and visit differ (see Table 4). — astro-ph.EP

We present two transit observations of the ∼520K, 1.85R, 4.0M super-Earth TOI-776b with JWST NIRSpec/G395H, resulting in a 2.8-5.2μm transmission spectrum.

Producing reductions using the ExoTiC-JEDI and Eureka! pipelines, we obtain a median transit depth precision of 34ppm for both visits and both reductions in spectroscopic channels 30 pixels wide (∼0.02μm).

We find that our independent reductions produce consistent transmission spectra, however, each visit shows differing overall structure. For both reductions, a flat line is preferred for Visit 1 while a flat line with an offset between the NRS1 and NRS2 detectors is preferred for Visit 2; however, we are able to correct for this offset during our modeling analysis following methods outlined in previous literature.

Using picaso forward models, we can rule out metallicities up to at least 100× solar with an opaque pressure of 10−3 bar to ≥3σ in all cases, however, the exact lower limit varies between the visits, with Visit 1 ruling out ≲100× solar while the lower limits for Visit 2 extend beyond ∼350× solar.

Our results add to the growing list of super-Earth atmospheric constraints by JWST, which provide critical insight into the diversity and challenges of characterizing terrestrial planets.

Lili Alderson, Sarah E. Moran, Nicole L. Wallack, Natasha E. Batalha, Nicholas F. Wogan, Anne Dattilo, Hannah R. Wakeford, Jea Adam Redai, Munazza K. Alam, Artyom Aguichine, Natalie M. Batalha, Anna Gagnebin, Peter Gao, James Kirk, Mercedes López-Morales, Annabella Meech, Johanna Teske, Angie Wolfgang

Comments: 17 pages, 7 figures, 4 tables. Accepted for publication in AJ. arXiv admin note: text overlap with arXiv:2404.00093
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2501.14596 [astro-ph.EP] (or arXiv:2501.14596v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2501.14596
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Related DOI:
https://doi.org/10.3847/1538-3881/adad64
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Submission history
From: Lili Alderson
[v1] Fri, 24 Jan 2025 16:08:00 UTC (4,483 KB)
https://arxiv.org/abs/2501.14596
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) 🖖🏻