Imaging & Spectroscopy

Early Release Science Of The Exoplanet WASP-39b With JWST NIRISS

By Keith Cowing
Press Release
November 21, 2022
Filed under , , , , , , , ,
Early Release Science Of The Exoplanet WASP-39b With JWST NIRISS
Interpretation of the constituents of the NIRISS WASP-39b transmission spectrum. (a/b): The top panel shows the comparison of WASP-39b’s transmission spectrum from the nirHiss reduction (grey points) with respect to the best-fit reference model (black line). Each colored line removes a key constituent found in our best-fit reference model to demonstrate how the spectrum would change were these features not included. The removal of clouds, and H2O absorption from the reference model result in large-scale changes to the shape and depth of the transmission spectrum. Other sources of opacity with an impact on the spectrum are K, CO, and CO2 . Residuals between the data and the reference model are plotted below. (c/d): The two bottom panels show the molecular absorption cross-sections for a selection of gases observable within the NIRISS bandpass. The middle panel highlights gases inferred by our analysis of WASP-39b’s spectrum. The bottom panel highlights some gases that were not identified in these data, but that may be present in future observations of other exoplanets. ( — astro-ph.EP

Transmission spectroscopy provides insight into the atmospheric properties and consequently the formation history, physics, and chemistry of transiting exoplanets. However, obtaining precise inferences of atmospheric properties from transmission spectra requires simultaneously measuring the strength and shape of multiple spectral absorption features from a wide range of chemical species.

This has been challenging given the precision and wavelength coverage of previous observatories. Here, we present the transmission spectrum of the Saturn-mass exoplanet WASP-39b obtained using the SOSS mode of the NIRISS instrument on the JWST.

This spectrum spans 0.6−2.8μm in wavelength and reveals multiple water absorption bands, the potassium resonance doublet, as well as signatures of clouds. The precision and broad wavelength coverage of NIRISS-SOSS allows us to break model degeneracies between cloud properties and the atmospheric composition of WASP-39b, favoring a heavy element enhancement (“metallicity”) of ∼10−30× the solar value, a sub-solar carbon-to-oxygen (C/O) ratio, and a solar-to-super-solar potassium-to-oxygen (K/O) ratio.

The observations are best explained by wavelength-dependent, non-gray clouds with inhomogeneous coverage of the planet’s terminator.

Adina D. Feinstein, Michael Radica, Luis Welbanks, Catriona Anne Murray, Kazumasa Ohno, Louis-Philippe Coulombe, Néstor Espinoza, Jacob L. Bean, Johanna K. Teske, Björn Benneke, Michael R. Line, Zafar Rustamkulov, Arianna Saba, Angelos Tsiaras, Joanna K. Barstow, Jonathan J. Fortney, Peter Gao, Heather A. Knutson, Ryan J. MacDonald, Thomas Mikal-Evans, Benjamin V. Rackham, Jake Taylor, Vivien Parmentier, Natalie M. Batalha, Zachory K. Berta-Thompson, Aarynn L. Carter, Quentin Changeat, Leonardo A. Dos Santos, Neale P. Gibson, Jayesh M Goyal, Laura Kreidberg, Mercedes López-Morales, Joshua D Lothringer, Yamila Miguel, Karan Molaverdikhani, Sarah E. Moran, Giuseppe Morello, Sagnick Mukherjee, David K. Sing, Kevin B. Stevenson, Hannah R. Wakeford, Eva-Maria Ahrer, Munazza K. Alam, Lili Alderson, Natalie H. Allen, Natasha E. Batalha, Taylor J. Bell, Jasmina Blecic, Jonathan Brande, Claudio Caceres, S. L. Casewell, Katy L. Chubb, Ian J.M. Crossfield, Nicolas Crouzet, Patricio E. Cubillos, Leen Decin, Jean-Michel Désert, Joseph Harrington, Kevin Heng, Thomas Henning, Nicolas Iro, Eliza M.-R. Kempton, Sarah Kendrew, James Kirk, Jessica Krick, Pierre-Olivier Lagage, Monika Lendl, Luigi Mancini, Megan Mansfield, E. M. May, N. J. Mayne, Nikolay K. Nikolov, Enric Palle, Dominique J.M. Petit dit de la Roche, Caroline Piaulet, Diana Powell, Seth Redfield, Laura K. Rogers, Michael T. Roman, Pierre-Alexis Roy, Matthew C. Nixon, Everett Schlawin, Xianyu Tan, P. Tremblin, Jake D. Turner, Olivia Venot, William C. Waalkes, Peter J. Wheatley, Xi Zhang

Comments: 48 pages, 12 figures, 2 tables. Under review at Nature
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2211.10493 [astro-ph.EP] (or arXiv:2211.10493v1 [astro-ph.EP] for this version)
Submission history
From: Adina Feinstein
[v1] Fri, 18 Nov 2022 20:01:34 UTC (7,388 KB)

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