Inhomogeneous terminators on the exoplanet WASP-39 b

• 成果类型: Article
• 署名作者: Espinoza, Nestor; Steinrueck, Maria E.; Kirk, James; MacDonald, Ryan J.; Savel, Arjun B.; Arnold, Kenneth; Kempton, Eliza M. -R.; Murphy, Matthew M.; Carone, Ludmila; Zamyatina, Maria; Lewis, David A.; Samra, Dominic; Kiefer, Sven; Rauscher, Emily; Christie, Duncan; Mayne, Nathan; Helling, Christiane; Rustamkulov, Zafar; Parmentier, Vivien; May, Erin M.; Carter, Aarynn L.; Zhang, Xi; Lopez-Morales, Mercedes; Allen, Natalie; Blecic, Jasmina; Decin, Leen; Mancini, Luigi; Molaverdikhani, Karan; Rackham, Benjamin V.; Palle, Enric; Tsai, Shang-Min; Ahrer, Eva-Maria; Bean, Jacob L.; Crossfield, Ian J. M.; Haegele, David; Hebrard, Eric; Kreidberg, Laura; Powell, Diana; Schneider, Aaron D.; Welbanks, Luis; Wheatley, Peter; Brahm, Rafael; Crouzet, Nicolas
• 署名单位: Space Telescope Science Institute; Johns Hopkins University; Max Planck Society; University of Chicago; Imperial College London; University of Michigan System; University of Michigan; University System of Maryland; University of Maryland College Park; University of Arizona; University of Arizona; Austrian Academy of Sciences; University of Exeter; Graz University of Technology; KU Leuven; University of St Andrews; Graz University of Technology; Universite Cote d'Azur; Observatoire de la Cote d'Azur; Centre National de la Recherche Scientifique (CNRS); Johns Hopkins University; Johns Hopkins University Applied Physics Laboratory; University of California System; University of California Santa Cruz; University of California System; University of California Santa Cruz; Smithsonian Institution; New York University; New York University Abu Dhabi; New York University; New York University Abu Dhabi; University of Rome Tor Vergata; Istituto Nazionale Astrofisica (INAF); University of Munich; Massachusetts Institute of Technology (MIT); Massachusetts Institute of Technology (MIT); Instituto de Astrofisica de Canarias; University of California System; University of California Riverside; University of Warwick; University of Kansas; University of Copenhagen; Niels Bohr Institute; Arizona State University; Arizona State University-Tempe; Universidad Adolfo Ibanez; Leiden University; Leiden University - Excl LUMC
• 刊物名称: Nature
• ISSN/ISSBN: 0028-6258
• DOI: 10.1038/s41586-024-07768-4
• 发表日期: 2024-08-29
• 关键词: general-circulation model; molecular line lists; transmission spectra; computer-program; brown dwarfs; hot jupiters; gas-phase; stellar; atmospheres; simulations

摘要

Transmission spectroscopy has been a workhorse technique used over the past two decades to constrain the physical and chemical properties of exoplanet atmospheres1-5. One of its classical key assumptions is that the portion of the atmosphere it probes-the terminator region-is homogeneous. Several works from the past decade, however, have put this into question for highly irradiated, hot (Teq greater than or similar to 1,000 K) gas giant exoplanets, both empirically6-10 and through three-dimensional modelling11-17. While models have predicted clear differences between the evening (day-to-night) and morning (night-to-day) terminators, direct morning and evening transmission spectra in a wide wavelength range have not been reported for an exoplanet so far. Under the assumption of precise and accurate orbital parameters for the exoplanet WASP-39 b, here we report the detection of inhomogeneous terminators on WASP-39 b, which has allowed us to retrieve its morning and evening transmission spectra in the near-infrared (2-5 mu m) using the James Webb Space Telescope. We have observed larger transit depths in the evening, which are, on average, 405 +/- 88 ppm larger than the morning ones, and also have qualitatively larger features than the morning spectrum. The spectra are best explained by models in which the evening terminator is hotter than the morning terminator by 177-57+65\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$17{7}_{-57}<^>{+65}$$\end{document} K, with both terminators having C/O ratios consistent with solar. General circulation models predict temperature differences broadly consistent with the above value and point towards a cloudy morning terminator and a clearer evening terminator. The atmospheric terminator region of WASP-39 b, a hot gas giant exoplanet, is inhomogeneous, despite past assumptions, with the evening terminator being hotter and thus probably clearer, and the morning terminator probably being cloudy and consequently cooler.