A planet orbiting a distant star has been discovered to have powerful iron winds whipping around its atmosphere.
The planet, named WASP-76 b, is an ultrahot Jupiter with temperatures over 4,350 degrees Fahrenheit and is located about 640 light-years away from Earth.
Previous research has spied strange "rainbows" and iron rain in its scalding-hot atmosphere, but according to a new paper in the journal Astronomy & Astrophysics, the day side of the planet is also buffeted by winds made of iron.
''This is the first time that such detailed optical observations have been made on the day side of this exoplanet, providing key data on its atmospheric structure,'' study co-author Ana Rita Costa Silva, a doctoral student at the Instituto de Astrofísica e Ciências do Espaço (IA), said in a statement. ''Our observations indicate the presence of powerful iron winds, probably fueled by a hotspot in the atmosphere.''
WASP-76 b orbits the star WASP-76 every 1.8 days, at a distance of only 3.3 percent the distance between the Earth and the sun. This ultrahot Jupiter has a mass of 0.92 Jupiters, but has a radius of about 1.85 times that of Jupiter's. Like many ultrahot Jupiters, WASP-76b is tidally locked, meaning one side of the planet permanently faces the star, while the other side is always in darkness. This leads to extreme temperature differences between the day and night sides.
In this new paper, researchers from the University of Geneva (UNIGE) in Switzerland and the PlanetS National Centre of Competence in Research describe how they used the ESPRESSO spectrograph on the ESO's Very Large Telescope (VLT) in Chile to examine the day-side atmosphere of WASP-76 b. There, researchers discovered a strange stream of iron atoms moving between the lower and upper layers of the planet's atmosphere.
''The work on WASP-76 b shows us just how extreme atmospheric conditions can be on ultrahot Jupiters,'' study co-author David Ehrenreich, an associate professor in the Astronomy Department at the UNIGE Faculty of Science, said in the statement.
''In-depth analysis of this type of planet provides us with valuable information for a better understanding of planetary climates as a whole'.'
Previous research into WASP-76 b found barium in its upper atmosphere, iron rain on its night side, and even a bizarre rainbow at the boundary between day and night. These findings, plus the new discoveries made thanks to ESPRESSO, will further aid astronomers' understanding of WASP-76 b's climate and the properties of other ultrahot Jupiters across the galaxy.
''ESPRESSO's ability to make such precise measurements is crucial,'' study co-author Christophe Lovis, associate professor in the Astronomy Department at the UNIGE Faculty of Science, said in the statement. ''This level of precision allows us to explore the dynamic processes in the atmospheres of exoplanets like WASP-76 b with an unprecedented level of detail.''
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Silva, A. R. C., Demangeon, O. D. S., Santos, N. C., Ehrenreich, D., Lovis, C., Chakraborty, H., Lendl, M., Pepe, F., Cristiani, S., Rebolo, R., Zapatero-Osorio, M. R., Adibekyan, V., Alibert, Y., Allart, R., Prieto, C. A., Silva, T. A., Borsa, F., Bourrier, V., Cristo, E., ... Udry, S. (2024). ESPRESSO reveals blueshifted neutral iron emission lines on the dayside of WASP-76 b. Astronomy & Astrophysics, 689, A8. https://doi.org/10.1051/0004-6361/202449935