Detection of Carbon Monoxide in the Atmosphere of WASP-39b Applying Standard Cross-correlation Techniques to JWST NIRSpec G395H Data

Creators: Esparza-Borges, Emma^{1, 2}; López-Morales, Mercedes³; Adams Redai, Jéa I.³; Pallé, Enric^{1, 2}; Kirk, James⁴; Casasayas-Barris, Núria¹; Batalha, Natasha E.⁵; Rackham, Benjamin V.⁶; Bean, Jacob L.⁷; Casewell, S. L.⁸; Decin, Leen⁹; Dos Santos, Leonardo A.¹⁰; Muñoz, Antonio García¹¹; Harrington, Joseph¹²; Heng, Kevin¹³; Hu, Renyu^{14, 15}; Mancini, Luigi^{16, 17, 18}; Molaverdikhani, Karan^{13, 19}; Morello, Giuseppe^{1, 20}; Nikolov, Nikolay K.¹⁰; Nixon, Matthew C.²¹; Redfield, Seth²²; Stevenson, Kevin B.²³; Wakeford, Hannah R.²⁴; Alam, Munazza K.²⁵; Benneke, Björn²⁶; Blecic, Jasmina²⁷; Crouzet, Nicolas²⁸; Daylan, Tansu²⁹; Inglis, Julie¹⁵; Kreidberg, Laura¹⁷; Petit dit de la Roche, Dominique J. M.³⁰; Turner, Jake D.³¹

1. Instituto de Astrofísica de Canarias
2. University of La Laguna
3. Harvard-Smithsonian Center for Astrophysics
4. Imperial College London
5. Ames Research Center
6. Massachusetts Institute of Technology
7. University of Chicago
8. University of Leicester
9. KU Leuven
10. Space Telescope Science Institute
11. University of Paris
12. University of Central Florida
13. Ludwig-Maximilians-Universität München
14. Jet Propulsion Lab
15. California Institute of Technology
16. University of Rome Tor Vergata
17. Max Planck Institute for Astronomy
18. INAF—Turin Astrophysical Observatory, Pino Torinese, Italy
19. Excellence Cluster Universe
20. Chalmers University of Technology
21. University of Maryland, College Park
22. Wesleyan University
23. Johns Hopkins University Applied Physics Laboratory
24. University of Bristol
25. Carnegie Earth & Planets Laboratory, 5241 Broad Branch Road NW, Washington, DC 20015, USA
26. University of Montreal
27. New York University Abu Dhabi
28. Leiden University
29. Princeton University
30. University of Geneva
31. Cornell University

Abstract

Carbon monoxide was recently reported in the atmosphere of the hot Jupiter WASP-39b using the NIRSpec PRISM transit observation of this planet, collected as part of the JWST Transiting Exoplanet Community Early Release Science Program. This detection, however, could not be confidently confirmed in the initial analysis of the higher-resolution observations with NIRSpec G395H disperser. Here we confirm the detection of CO in the atmosphere of WASP-39b using the NIRSpec G395H data and cross-correlation techniques. We do this by searching for the CO signal in the unbinned transmission spectrum of the planet between 4.6 and 5.0 μm, where the contribution of CO is expected to be higher than that of other anticipated molecules in the planet's atmosphere. Our search results in a detection of CO with a cross-correlation function (CCF) significance of 6.6σ when using a template with only ¹²C¹⁶O lines. The CCF significance of the CO signal increases to 7.5σ when including in the template lines from additional CO isotopologues, with the largest contribution being from ¹³C¹⁶O. Our results highlight how cross-correlation techniques can be a powerful tool for unveiling the chemical composition of exoplanetary atmospheres from medium-resolution transmission spectra, including the detection of isotopologues.

Copyright and License

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

This work is based on observations made with the NASA/ESA/CSA JWST. 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. The specific observations can be accessed via doi:10.17909/gdm2-0q65. These observations are associated with program JWST-ERS-01366. Support for program JWST-ERS-01366 was provided by NASA through a grant from the Space Telescope Science Institute. This work was supported by grant JWST-ERS-01366.033-A. E.E-B and E.P. acknowledge funding from the Spanish Ministry of Economics and Competitiveness through project PGC2018-098153-B-C31. E.E-B acknowledges financial support from the European Union and the State Agency of Investigation of the Spanish Ministry of Science and Innovation (MICINN) under the grant PRE2020-093107 of the Pre-Doc Program for the Training of Doctors (FPI-SO) through FSE funds. J.K. acknowledges financial support from Imperial College London through an Imperial College Research Grant.

Facilities

JWST (NIRSpec) - James Webb Space Telescope.

Software References

batman (Kreidberg 2015), emcee (Foreman-Mackey et al. 2013), ExoTIC-LD (Grant & Wakeford 2022), george (Ambikasaran et al. 2015), petitRADTRANS (Mollière et al. 2019), PyAstronomy (Czesla et al. 2019, https://github.com/sczesla/PyAstronomy), spectres (Carnall 2017), scipy (Virtanen et al. 2020), Tiberius (Kirk et al. 2017, 2018, 2019, 2021).

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