No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c
- Creators
- Zieba, Sebastian
- Kreidberg, Laura
- Ducrot, Elsa
- Gillon, Michaël
- Morley, Caroline
- Schaefer, Laura
- Tamburo, Patrick
- Koll, Daniel D. B.
- Lyu, Xintong
- Acuña, Lorena
- Agol, Eric
- Iyer, Aishwarya R.
- Hu, Renyu
- Lincowski, Andrew P.
- Meadows, Victoria S.
- Selsis, Franck
- Bolmont, Emeline
- Mandell, Avi M.
- Suissa, Gabrielle
Abstract
Seven rocky planets orbit the nearby dwarf star TRAPPIST-1, providing a unique opportunity to search for atmospheres on small planets outside the Solar System. Thanks to the recent launch of the James Webb Space Telescope (JWST), possible atmospheric constituents such as carbon dioxide (CO₂) are now detectable. Recent JWST observations of the innermost planet TRAPPIST-1 b showed that it is most probably a bare rock without any CO₂ in its atmosphere. Here we report the detection of thermal emission from the dayside of TRAPPIST-1 c with the Mid-Infrared Instrument (MIRI) on JWST at 15 µm. We measure a planet-to-star flux ratio of f_p/f⁎ = 421 ± 94 parts per million (ppm), which corresponds to an inferred dayside brightness temperature of 380 ± 31 K. This high dayside temperature disfavours a thick, CO₂-rich atmosphere on the planet. The data rule out cloud-free O₂/CO₂ mixtures with surface pressures ranging from 10 bar (with 10 ppm CO₂) to 0.1 bar (pure CO₂). A Venus-analogue atmosphere with sulfuric acid clouds is also disfavoured at 2.6σ confidence. Thinner atmospheres or bare-rock surfaces are consistent with our measured planet-to-star flux ratio. The absence of a thick, CO₂-rich atmosphere on TRAPPIST-1 c suggests a relatively volatile-poor formation history, with less than 9.5^(+7.5)_(−2.3) Earth oceans of water. If all planets in the system formed in the same way, this would indicate a limited reservoir of volatiles for the potentially habitable planets in the system.
Additional Information
© The Author(s) 2023. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. This work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programme 2304. M.G. is F.R.S.-FNRS Research Director and acknowledges support from the Belgian Federal Science Policy Office (BELSPO) BRAIN 2.0 (Belgian Research Action through Interdisciplinary Networks) for the project PORTAL no. B2/212/P1/PORTAL (PhOtotrophy on Rocky habiTAble pLanets). V.S.M. and A.P.L. are part of the Virtual Planetary Laboratory Team, which is a member of the NASA Nexus for Exoplanet System Science, and financed through NASA Astrobiology Program grant 80NSSC18K0829. A.R.I. acknowledges support from the NASA FINESST grant 80NSSC21K1846. Open access funding provided by Max Planck Society. Contributions. S.Z., L.K., M.G., P.T., E.D., A.P.L., V.S.M., D.D.B.K., C.M., L.S., E.A., L.A. and G.S. contributed notably to the writing of this manuscript. S.Z., E.D., P.T. and M.G. provided a data reduction and data analysis of the four visits for this work and contributed an eclipse depth value. C.M., D.D.B.K., X.L., R.H., A.P.L. and V.S.M. ran theoretical models for the planet's atmosphere and surface. L.A. ran models on the planet's interior structure. A.R.I. and E.A. modelled the stellar spectrum. L.S. modelled the atmospheric escape for the planet. L.K., M.G., V.S.M., D.D.B.K., R.H., C.M., L.S., E.A., F.S., E.B. and A.M.M. contributed to the observing proposal. E.D. is Paris Region Fellow, Marie Sklodowska-Curie Action. Data availability. The data used in this work were collected by the James Webb Space Telescope as part of General Observer programme 2304 and will be publicly accessible after the default proprietary period of one year. The most recently taken visit will therefore be publicly accessible on the Mikulski Archive for Space Telescopes on 1 December 2023. Code availability. We used the following codes, resources and Python packages to reduce, analyse and interpret our JWST observations of TRAPPIST-1 c: numpy, matplotlib, astropy, batman, Eureka!, jwst, emcee, trafit, dynesty, SMART, VPL Climate, DISORT and IRAF/DAOPHOT. We can share the code used in the data reduction or data analysis on request. The authors declare no competing interests.Attached Files
Supplemental Material - 41586_2023_6232_Fig10_ESM.jpg
Supplemental Material - 41586_2023_6232_Fig5_ESM.jpg
Supplemental Material - 41586_2023_6232_Fig6_ESM.jpg
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Supplemental Material - 41586_2023_6232_Tab3_ESM.jpg
Supplemental Material - 41586_2023_6232_Tab4_ESM.jpg
In Press - s41586-023-06232-z.pdf
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Additional details
- Eprint ID
- 122090
- Resolver ID
- CaltechAUTHORS:20230630-22239000.5
- DOI
- 10.1038/s41586-023-06232-z
- PMCID
- PMC10447244
- NAS 5-03127
- NASA
- Fonds de la Recherche Scientifique (FNRS)
- B2/212/P1/PORTAL
- Belgian Federal Science Policy Office (BELSPO)
- 80NSSC18K0829
- NASA
- 80NSSC21K1846
- NASA
- Max Planck Society
- Created
-
2023-07-01Created from EPrint's datestamp field
- Updated
-
2023-07-01Created from EPrint's last_modified field