Retrieval of the dayside atmosphere of WASP-43b with CRIRES<SUP>+</SUP>

DOI: 
10.1051/0004-6361/202347151
Publication date: 
11/10/2023
Main author: 
Lesjak, F.
IAA authors: 
Shulyak, D.
Authors: 
Lesjak, F.;Nortmann, L.;Yan, F.;Cont, D.;Reiners, A.;Piskunov, N.;Hatzes, A.;Boldt-Christmas, L.;Czesla, S.;Heiter, U.;Kochukhov, O.;Lavail, A.;Nagel, E.;Rains, A. D.;Rengel, M.;Rodler, F.;Seemann, U.;Shulyak, D.
Journal: 
Astronomy and Astrophysics
Publication type: 
Article
Volume: 
678
Pages: 
A23
Abstract: 
Accurately estimating the C/O ratio of hot Jupiter atmospheres is a promising pathway towards understanding planet formation and migration, as well as the formation of clouds and the overall atmospheric composition. The atmosphere of the hot Jupiter WASP-43b has been extensively analysed using low-resolution observations with HST and Spitzer, but these previous observations did not cover the K band, which hosts prominent spectral features of major carbon-bearing species such as CO and CH<SUB>4</SUB>. As a result, the ability to establish precise constraints on the C/O ratio was limited. Moreover, the planet has not been studied at high spectral resolution, which can provide insights into the atmospheric dynamics. In this study, we present the first high-resolution dayside spectra of WASP-43b with the new CRIRES<SUP>+</SUP> spectrograph. By observing the planet in the K band, we successfully detected the presence of CO and provide evidence for the existence of H<SUB>2</SUB>O using the cross-correlation method. This discovery represents the first direct detection of CO in the atmosphere of WASP-43b. Furthermore, we retrieved the temperature-pressure profile, abundances of CO and H<SUB>2</SUB>O, and a super-solar C/O ratio of 0.78 by applying a Bayesian retrieval framework to the data. Our findings also shed light on the atmospheric characteristics of WASP-43b. We found no evidence for a cloud deck on the dayside, and recovered a line broadening indicative of an equatorial super-rotation corresponding to a jet with a wind speed of ~5kms<SUP>−1</SUP>, matching the results of previous forward models and low-resolution atmospheric retrievals for this planet.
Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2023A&A...678A..23L/abstract
ADS Bibcode: 
2023A&A...678A..23L
Keywords: 
planets and satellites: atmospheres;techniques: spectroscopic;planets and satellites: individual: WASP-43b;Astrophysics - Earth and Planetary Astrophysics