Nightside condensation of iron in an ultrahot giant exoplanet
Journal
Date Issued
2020
Author(s)
Ehrenreich, David
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Lovis, Christophe
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Allart, Romain
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Zapatero Osorio, María Rosa
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Pepe, Francesco
•
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Rebolo, Rafael
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Santos, Nuno C.
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•
Demangeon, Olivier
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Dumusque, Xavier
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González Hernández, Jonay I.
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Casasayas-Barris, Núria
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Ségransan, Damien
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Sousa, Sérgio
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Abreu, Manuel
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Adibekyan, Vardan
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Affolter, Michael
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Allende Prieto, Carlos
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Alibert, Yann
•
•
Alves, David
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Amate, Manuel
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Avila, Gerardo
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•
Bandy, Timothy
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Benz, Willy
•
•
Bolmont, Émeline
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Bouchy, François
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Bourrier, Vincent
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Broeg, Christopher
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Cabral, Alexandre
•
•
Pallé, Enric
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Cegla, H. M.
•
•
Coelho, João M. P.
•
•
•
Cumani, Claudio
•
•
Dekker, Hans
•
•
Deiries, Sebastian
•
•
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Figueira, Pedro
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Fragoso, Ana
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Genolet, Ludovic
•
•
Génova Santos, Ricardo
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Hara, Nathan
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Hughes, Ian
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Iwert, Olaf
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Kerber, Florian
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Knudstrup, Jens
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Lavie, Baptiste
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Lizon, Jean-Louis
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Lendl, Monika
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Lo Curto, Gaspare
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Maire, Charles
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Manescau, Antonio
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Martins, C. J. A. P.
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Mégevand, Denis
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Mehner, Andrea
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Modigliani, Andrea
•
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Monteiro, Manuel
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Monteiro, Mario
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Moschetti, Manuele
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Müller, Eric
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Nunes, Nelson
•
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Oliveira, António
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Pasquini, Luca
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Rasilla, José Luis
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•
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Santana Tschudi, Samuel
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Santin, Paolo
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Santos, Pedro
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Segovia Milla, Alex
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Seidel, Julia V.
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Sosnowska, Danuta
•
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Spanò, Paolo
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Suárez Mascareño, Alejandro
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Tabernero, Hugo
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Tenegi, Fabio
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Udry, Stéphane
•
•
Abstract
Ultrahot giant exoplanets receive thousands of times Earth's insolation1,2. Their high-temperature atmospheres (greater than 2,000 kelvin) are ideal laboratories for studying extreme planetary climates and chemistry3-5. Daysides are predicted to be cloud-free, dominated by atomic species6 and much hotter than nightsides5,7,8. Atoms are expected to recombine into molecules over the nightside9, resulting in different day and night chemistries. Although metallic elements and a large temperature contrast have been observed10-14, no chemical gradient has been measured across the surface of such an exoplanet. Different atmospheric chemistry between the day-to-night (`evening') and night-to-day (`morning') terminators could, however, be revealed as an asymmetric absorption signature during transit4,7,15. Here we report the detection of an asymmetric atmospheric signature in the ultrahot exoplanet WASP-76b. We spectrally and temporally resolve this signature using a combination of high-dispersion spectroscopy with a large photon-collecting area. The absorption signal, attributed to neutral iron, is blueshifted by -11 ± 0.7 kilometres per second on the trailing limb, which can be explained by a combination of planetary rotation and wind blowing from the hot dayside16. In contrast, no signal arises from the nightside close to the morning terminator, showing that atomic iron is not absorbing starlight there. We conclude that iron must therefore condense during its journey across the nightside.
Volume
580
Issue
7805
Start page
597
Issn Identifier
0028-0836
Ads BibCode
2020Natur.580..597E
Rights
open.access
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