JWST COMPASS: The First Near- to Mid-infrared Transmission Spectrum of the Hot Super-Earth L 168-9 b
Abstract We present the first broadband near- to mid-infrared (3–12 μ m) transmission spectrum of the highly irradiated ( T eq = 981 K) M-dwarf rocky planet L 168-9 b (TOI-134 b) observed with the Near-infrared Spectrograph and Mid-infrared Instrument (MIRI) instruments aboard JWST. We measure the near-infrared transit depths to a combined median precision of 20 ppm across the three visits in 54 spectroscopic channels with uniform widths of 60 pixels (∼0.2 μ m wide; R ∼ 100), and the mid-infrared transit depths to 61 ppm median precision in 48 wavelength bins (∼0.15 μ m wide; R ∼ 50). We compare the transmission spectrum of L 168-9 b to a grid of 1D thermochemical equilibrium forward models, and rule out atmospheric metallicities of less than 100× solar (mean molecular weights <4 g mol −1 ) to 3 σ confidence assuming high surface pressure (>1 bar), cloudless atmospheres. Based on photoevaporation models for L 168-9 b with initial atmospheric mass fractions ranging from 2% to 100%, we find that this planet could not have retained a primordial H/He atmosphere beyond the first 200 Myr of its lifetime. Follow-up MIRI eclipse observations at 15 μ m could make it possible to confidently identify a CO 2 -dominated atmosphere on this planet if one exists.
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)
- Annabella Meech (ORCID: https://orcid.org/0000-0002-7500-7173)
- 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)
- 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)
- Anne Dattilo (ORCID: https://orcid.org/0000-0002-1092-2995)
- 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)
- 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)
- Carnegie Observatories (US)
- Eureka Scientific (US)
- Imperial College London (GB)
Publication Details
- Journal
- The Astronomical Journal
- Published
- 2024-12-10
- DOI
- https://doi.org/10.3847/1538-3881/ad8eb5
- Citations
- 19
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 6.30
Funders
- National Aeronautics and Space Administration
- Alfred P. Sloan Foundation
- Space Telescope Science Institute
- Science and Technology Facilities Council