Identification by the Webb Space Telescope of carbon dioxide in an exoplanet atmosphere – Astrobiology

Identification by the Webb Space Telescope of carbon dioxide in an exoplanet atmosphere

JWST NIRpec time series data for WASP-39b. a) Spectroscopic light curves for the transit of WASP-39b with a spectral resolving power of 20 and a time frame of 1 minute (data are clustered and vertically shifted for display purposes only). An exoplanetary lightcurve model was fitted to the data using a quadratic law of limb darkening with an exponential ramp and a suppressed quadratic time function. b) Residuals of the pooled light curve after subtracting the transit model scaled by a factor of five to show structure. RMS residues are given in units of ppm. The numbers in parentheses are the ratio of the RMS to the predicted photon-limited noise.


Carbon dioxide (CO2) is a key chemical species found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the enrichment in metals (i.e. in elements heavier than helium, also called “metallicity”), and therefore of the processes of formation of primary atmospheres hot gas giants.

It is also one of the most promising species to detect in the secondary atmospheres of terrestrial exoplanets. Previous photometric measurements of transiting planets with the Spitzer Space Telescope gave clues to the presence of CO2 but did not yield definitive detections due to the lack of unambiguous spectroscopic identification.

Here we present the detection of CO2 in the atmosphere of the gas giant exoplanet WASP-39b from transmission spectroscopy observations obtained with JWST as part of the Early Release Science Program (ERS). The data used in this study covers a wavelength of 3.0 to 5.5 {\mu}m and shows a prominent CO2 absorption feature at 4.3 {\mu}m (significance of 26{\ sigma}). The global spectrum fits well with one-dimensional 10x solar metallicity models that assume radiative-convective-thermochemical equilibrium and have moderate cloud opacity.

These models predict that the atmosphere should contain water, carbon monoxide and hydrogen sulphide in addition to CO2, but little methane. In addition, we also tentatively detect a small absorption feature near 4.0 {\mu}m which is not reproduced by these models.

JWST Transiting Exoplanet Community Early Release Science Team: Eva-Maria Ahrer (1 and 2), Lili Alderson (3), Natalie M. Batalha (4), Natasha E. Batalha (5), Jacob L. Bean (6) , Thomas G. Beatty (7), Taylor J. Bell (8), Björn Benneke (9), Zachory K. Berta-Thompson (10), Aarynn L. Carter (4), Ian JM Crossfield (11), Néstor Espinoza (12 and 13), Adina D. Feinstein (6 and 14), Jonathan J. Fortney (4), Neale P. Gibson (15), Jayesh M. Goyal (16), Eliza M. -R. Kempton (17), James Kirk (18), Laura Kreidberg (19), Mercedes López-Morales (18), Michael R. Line (20), Joshua D. Lothringer (21), Sarah E. Moran (22), Sagnick Mukherjee (4), Kazumasa Ohno (4), Vivien Parmentier (23 and 24), Caroline Piaulet (9), Zafar Rustamkulov (25), Everett Schlawin (26), David K. Sing (25 and 13), Kevin B. Stevenson (26), Hannah R. Wakeford (3), Natalie H. Allen (13 and 14), Stephan M. Birkmann (27), Jonathan Brande (11), Nicolas Crouzet (28), Patricio E. Cubillos (29 and 30), Mario Damiano (31), Jean-Michel Désert (32), Peter Gao (33), Joseph Harrington (34), Renyu Hu (31 and 35), Sarah Kendrew (27), Heather A. Knutson (35) , Pierre-Olivier Lagage (36), Jérémy Leconte (37), Monika Lendl (38), Ryan J. MacDonald (39), EM May (26), Yamila Miguel (28 and 40), Karan Molaverdikhani (41 and 42 and 19), Julianne I. Moses (43), Catriona Anne Murray (10), Molly Nehring (10), Nikolay K. Nikolov (12), DJM Petit dit de la Roche (38), Michael Radica (9), Pierre- Alexis Roy (9), Kevin G. Stassun (44), Jake Taylor (9), William C. Waalkes (10), Patcharapol Wachiraphan (10), Luis Welbanks (20 and 45), Peter J. Wheatley (2 and 1), Keshav Aggarwal (46) , Munazza K. Alam (33), Agnibha Banerjee (47), Joanna K. Barstow (47), Jasmina Blecic (48), SL Casewell (49), Quentin Changeat (50), KL Chubb (51), Knicole D Colón (52), Louis-Philippe Coulombe (9), Tansu Daylan (53 and 54), Miguel de Val-Borro (55), Leen Decin (56), Leonardo A. Dos Santos (12), Laura Flagg (39), Kevin France (57), Guangwei Fu (17 and 13), A. García Muñoz (36), John E. Gizis (58), Ana Glidden (59 and 60), David Grant (3), Kevin Heng (61), Thomas Henning (19), Yu-Cian Hong (39), Julie Inglis (35), Nicolas Iro (62), Tiffany Kataria (31), Thaddeus D. Komacek (17), Jessica E. Krick (63), Elspeth KH Lee (64), Nikole K. Lewis (39), Jorge Lillo-Box (65), Jacob Lustig-Yaeger (26), Luigi Mancini (66 and 19 and 67), Avi M. Mandell et al. (32 additional authors not represented)

Comments: 27 pages, 6 figures, Accepted for publication in Nature, data and models available at https://doi.
Subjects: Terrestrial and planetary astrophysics (astro-ph.EP)
Cite as: arXiv:2208.11692 [astro-ph.EP] (or arXiv:2208.11692v1 [astro-ph.EP] for this release)
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From: Natalie Batalha Dr.
[v1] Wed Aug 24 2022 5:52:36 PM UTC (2,186 KB)
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Astrobiology, Astrochemistry

#Identification #Webb #Space #Telescope #carbon #dioxide #exoplanet #atmosphere #Astrobiology

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