JWST COMPASS: The 3–5 μm Transmission Spectrum of the Super-Earth L 98-59 c
Abstract We present a JWST Near-InfraRed Spectrograph (NIRSpec) transmission spectrum of the super-Earth exoplanet L 98-59 c. This small ( R p = 1.385 ± 0.085 R ⊕ , M p = 2.22 ± 0.26 R ⊕ ), warm ( T eq = 553 K) planet resides in a multiplanet system around a nearby, bright ( J = 7.933) M3V star. We find that the transmission spectrum of L 98-59 c is featureless at the precision of our data. We achieve precisions of 22 ppm in NIRSpec G395H’s NRS1 detector and 36 ppm in the NRS2 detector at a resolution R ∼ 200 (30 pixel wide bins). At this level of precision, we are able rule out primordial H 2 –He atmospheres across a range of cloud pressure levels up to at least ∼0.1 mbar. By comparison to atmospheric forward models, we also rule out atmospheric metallicities below ∼300× solar at 3 σ (or, equivalently, atmospheric mean molecular weights below ∼10 g mol −1 ). We also rule out pure methane atmospheres. The remaining scenarios that are compatible with our data include a planet with no atmosphere at all, or higher-mean-molecular-weight atmospheres, such as CO 2 - or H 2 O-rich atmospheres. This study adds to a growing body of evidence suggesting that planets ≲1.5 R ⊕ lack extended atmospheres.
Authors
- Natasha E. Batalha (ORCID: https://orcid.org/0000-0003-1240-6844)
- Mercedes López‐Morales (ORCID: https://orcid.org/0000-0003-3204-8183)
- Jéa Adams Redai (ORCID: https://orcid.org/0000-0002-4489-3168)
- Nicholas Scarsdale (ORCID: https://orcid.org/0000-0003-3623-7280)
- Munazza K. Alam (ORCID: https://orcid.org/0000-0003-4157-832X)
- Nicole L. Wallack (ORCID: https://orcid.org/0000-0003-0354-0187)
- Nicholas F. Wogan (ORCID: https://orcid.org/0000-0002-0413-3308)
- Tyler A. Gordon (ORCID: https://orcid.org/0000-0001-5253-1987)
- Johanna Teske (ORCID: https://orcid.org/0009-0008-2801-5040)
- Peter Gao (ORCID: https://orcid.org/0000-0002-8518-9601)
- Sarah E. Moran (ORCID: https://orcid.org/0000-0002-6721-3284)
- James Kirk (ORCID: https://orcid.org/0000-0002-4207-6615)
- Angie Wolfgang (ORCID: https://orcid.org/0000-0003-2862-6278)
- Lili Alderson (ORCID: https://orcid.org/0000-0001-8703-7751)
- Natalie M. Batalha (ORCID: https://orcid.org/0000-0002-7030-9519)
- Hannah R. Wakeford (ORCID: https://orcid.org/0000-0003-4328-3867)
- Artyom Aguichine (ORCID: https://orcid.org/0000-0002-8949-5956)
Institutions
- Ames Research Center (US)
- Space Telescope Science Institute (US)
- Planetary Science Institute (US)
- University of Arizona (US)
- University of California, Santa Cruz (US)
- Carnegie Institution for Science (US)
- University of Bristol (GB)
- Université Bourgogne Franche-Comté (FR)
- Center for Astrophysics Harvard & Smithsonian (US)
- Eureka Scientific (US)
- Imperial College London (GB)
Publication Details
- Journal
- The Astronomical Journal
- Published
- 2024-11-19
- DOI
- https://doi.org/10.3847/1538-3881/ad73cf
- Citations
- 21
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 6.96
Funders
- National Aeronautics and Space Administration
- Alfred P. Sloan Foundation
- California Institute of Technology
- Space Telescope Science Institute
- Government of the United Kingdom
- UK Research and Innovation
- Heising-Simons Foundation
- Indian Council of Agricultural Research
- Nuclear Safety and Security Commission
- HORIZON EUROPE Framework Programme
- Science and Technology Facilities Council
- Eurostars