Confirmation of TiO absorption and tentative detection of MgH and CrH in the atmosphere of HAT-P-41b

¹ CAS Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, No. 10 Yuanhua Road, Qixia District, 210023 Nanjing, PR China
e-mail: guochen@pmo.ac.cn
² School of Astronomy and Space Science, University of Science and Technology of China, No. 96 Jinzhai Road, Baohe District, 230026 Hefei, PR China
³ CAS Center for Excellence in Comparative Planetology, No. 96 Jinzhai Road, Baohe District, 230026 Hefei, PR China
⁴ Instituto de Astrofísica de Canarias (IAC), Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
⁵ Departamento de Astrofísica, Universidad de La Laguna (ULL), C/ Padre Herrera, 38206 La Laguna, Tenerife, Spain

Received: 15 September 2023
Accepted: 21 November 2023

Abstract

Understanding the role of optical absorbers is critical for linking the properties of the dayside and terminator atmospheres of hot Jupiters. This study aims to identify the signatures of optical absorbers in the atmosphere of the hot Jupiter HAT-P-41b. We conducted five transit observations of this planet to obtain its optical transmission spectra using the Gran Telescopio Canarias (GTC). We performed atmospheric retrievals assuming free abundances of 12 chemical species. Our Bayesian model comparisons revealed strong evidence for TiO absorption (∆ ln 𝒵 = 21.02), modest evidence for CrH (∆ ln 𝒵 = 3.73), and weak evidence for MgH (∆ ln 𝒵 = 2.32). When we combined the GTC transmission spectrum with previously published Hubble Space Telescope and Spitzer data, the retrieval results and model inferences remained consistent. In conclusion, HAT-P-41b has a metal-rich atmosphere with no high-altitude clouds or hazes. Further observations of its dayside atmosphere should be made to confirm the hints of a thermal inversion in the upper atmosphere suggested by our results.