Astronomers at the Thuringian State Observatory have teamed up with international researchers and measured supersonic winds around the equator of WASP-127b, a giant exoplanet. These supersonic jets can reach speeds up to 33.000 kilometers per hour. The discovery provides unique insights into the weather patterns of a distant world.
Up until a few years ago, astronomers could only measure the mass and the radius of extrasolar planets (planets around other stars than our Sun). Now, high-resolution instruments like CRIRES+ at the European Southern Observatory's Very Large Telescope enable scientists to learn more about the dynamics of an exoplanet’s atmosphere.
A team of astronomers, led by Dr. Lisa Nortmann at Georg-August-Universität in Göttingen, studied the atmosphere of the exoplanet WASP-127b using high-resolution infrared spectroscopy. WASP-127b is a type of exoplanet known as a "hot Jupiter" due to its large size and close orbit around its host star. The giant gas planet is slightly larger than Jupiter, but only has a fraction of its mass. Its host star WASP-127 is located over 500 light-years away from Earth.
The planet cannot be observed directly because it is too far away, and the star shines too bright. To find out more about the planet’s atmosphere, the team used an indirect approach: When the planet transits in front of its star, the light of the star travels through the planet's upper atmosphere. The planet's atmosphere blocks certain parts of the star light. Researchers can learn more about the atmosphere based on which parts of the star light are blocked.
Supersonic Winds around the Planet's Equator
The team detected water vapor (H₂O) and carbon monoxide (CO). The speed of the molecules in the atmosphere can be measured. To their big surprise, the researchers have detected two opposing velocity signals. One part of the atmosphere is moving toward the observers at an astonishing speed of nine kilometers per second (almost 33.000 kilometers per hour), while another part is moving away from the observers at the same speed.
Astronomers have measured supersonic jet winds on WASP-127b, a giant gas planet located about 520 light-years from Earth. Credit: ESOThe researchers conclude that extremely strong winds circulate at supersonic speed at the equator of the exoplanet WASP-127b. The equatorial jet wind moves nearly six times as fast as the planet rotates. “This is something we haven’t seen before,” Lisa Nortmann, lead author of the study, points out.
The extreme wind speeds and the clearly separated signals enable the astronomers to analyze different regions separately. The atmosphere is slightly hotter where the jet stream moves from the bright to the dark side of the planet in comparison to the opposite side (where the jet stream enters the bright side coming from the dark side). There are also differences between the equator and the poles. Since there are no strong signals from the poles, it can be assumed that the climate is colder there.
Distant stars and their planets are observed as point sources while planets in our Solar System can be observed with spatial resolution. "It is exciting to be able to detect differences in various regions of an exoplanet inspite the missing spatial resolution," Nortmann explains the novelty of the results.
A better understanding of weather on distant worlds
Artie Hatzes, scientist at the Thuringian state observatory, is part of the research team and lead the consortium that built the CRIRES+ instrument. He is very content that the high-resolution spectrograph provides such amazing results. „It is great that CRIRES+ at the European Southern Observatory's Very Large Telescope can detect such details in the atmosphere of extrasolar planets. Our understanding of these distant worlds is growing. The results complement observations made with space telescopes". Currently, such research can only be done with ground-based observatories because the instruments on satellite telescopes do not have the necessary velocity precision.
These measurements are a good basis for further research into exoplanet atmospheres. “The detailed mapping of the atmosphere of WASP-127b offers the opportunity to test theoretical circulation models,” Nortmann emphasizes. WASP-127b, with its unique atmospheric characteristics and rapid winds, provides a fascinating case study of atmospheric dynamics on planets far beyond our solar system.
More Information
The research was presented in the paper „CRIRES+ Transmission Spectroscopy of WASP-127b: Detection of Resolved Signatures of a Supersonic Equatorial Jet and Cool Poles in a Hot Planet“ , published today in „Astronomy & Astrophysics“.
* The team is composed of Lisa Nortmann (Institut für Astrophysik und Geophysik, Georg-August-Universität, Göttingen, Germany [IAG]), Fabio Lesjak (IAG), Fei Yan (Department of Astronomy, University of Science and Technology of China, Hefei, China), David Cont (Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München, Germany; Exzellenzcluster Origins, Garching, Germany), Stefan Czesla (Thüringer Landessternwarte Tautenburg, Germany [TLS]), Alexis Lavail (Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, France), Adam D. Rains (Department of Physics and Astronomy, Uppsala University, Sweden [Uppsala University]), Evangelos Nagel (IAG), Linn Boldt-Christmas (Uppsala University), Artie Hatzes (TLS), Ansgar Reiners (IAG), Nikolai Piskunov (Uppsala University), Oleg Kochukhov (Uppsala University), Ulrike Heiter (Uppsala University), Denis Shulyak (Instituto de Astrofísica de Andalucía, Glorieta de la Astronomía, Spain), Miriam Rengel (Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany), and Ulf Seemann (European Southern Observatory, Garching, Germany).
Additional Links:
NASA-Webseite: Details about the extrasolar planet WASP-127b
Press release European Southern Observatory (with video and images)
Contact:
Prof. Dr. Artie Hatzes
Thüringer Landessternwarte
Sternwarte 5
07778 Tautenburg
Dr. Lisa Nortmann
Georg-August-Universität Göttingen
Tel: +49 1515 119 54 35