Astronomers Unveil Wild Jet-Stream Winds on Distant Exoplanet

WASHINGTON — In the upper atmosphere of Earth, a rapidly moving air mass known as the jet stream blows with speeds exceeding 275 miles per hour, although these are not the most powerful in our solar system. The similarly positioned high-altitude winds on Neptune can attain velocities of about 1,200 miles per hour. However, those are merely a light breeze when contrasted with the jet-stream winds found on a planet named WASP-127b.

Astronomers have found winds roaring at approximately 20,500 miles per hour on this massive gas planet, situated in our Milky Way galaxy roughly 520 light-years away from Earth in a close orbit around a star akin to our sun. A light-year is the distance light traverses in a year, equating to 5.9 trillion miles.

The supersonic jet-stream winds circulating around WASP-127b at its equator are the fastest of their kind observed on any known celestial body.

“There is an incredibly rapid circumplanetary jet wind identified on this planet. The speed of these winds is astonishingly high,” noted astrophysicist Lisa Nortmann from the University of Göttingen in Germany, the principal author of the study published on Tuesday in the journal Astronomy & Astrophysics.

Over 5,800 planets outside our solar system — referred to as exoplanets — have been uncovered. WASP-127b is classified as a “hot Jupiter,” a gas giant that orbits extremely close to its host star. The diameter of WASP-127b is approximately 30% more extensive than that of Jupiter, the largest planet in our solar system. However, its mass is only around 16% that of Jupiter, making it one of the least dense — most inflated — planets ever recorded.

“WASP-127b is a gas giant, meaning it lacks a rocky or solid surface beneath its atmospheric layers. Instead, what lies beneath the visible atmosphere is gas that becomes denser and more pressurized the deeper one ventures into the planet,” explained astrophysicist and study co-author David Cont from Ludwig Maximilian University of Munich in Germany.

It completes an orbit around its star approximately every four days at nearly 5% of the distance that separates Earth from the sun, resulting in extreme exposure to stellar radiation. Similar to how our moon behaves relative to Earth, one hemisphere of WASP-127b constantly faces its star — known as the day side. The opposing side always turns away — designated as the night side. The temperature of its atmosphere reaches about 2,060 degrees Fahrenheit, with its polar regions being somewhat cooler than elsewhere.

Like Jupiter, WASP-127b primarily consists of hydrogen and helium, but its atmosphere also features traces of more complex molecules, such as carbon monoxide and water, which were identified in this investigation.

The fact that the day side of a hot Jupiter experiences high irradiation is thought to be a significant factor driving atmospheric dynamics.

“Determining what causes these powerful winds is complex, as multiple elements affect wind patterns in the atmospheres of exoplanets,” Cont stated.

“The main energy source for these winds is the intense irradiation from the host star,” Cont elaborated, though numerous factors significantly contribute to the formation of wind patterns.

Increased atmospheric wind speeds have been noticed on two additional exoplanets, with winds transferring from their day side to night side, but not in winds circulating around the entire planet.

The researchers monitored the velocity of molecules in the planet’s atmosphere utilizing an instrument known as CRIRES+ on the European Southern Observatory’s Very Large Telescope in Chile. They made their observations employing the “transit” technique, noting variations in the brightness of the host star when the planet moves across its path, from the perspective of an observer on Earth.

With advancements in instruments, observational methodologies, and data interpretation, researchers are improving their comprehension of exoplanets’ atmospheres.

“We are transcending beyond merely deducing average characteristics, like global mean temperature or chemical concentrations, to investigating the three-dimensional components of these atmospheres — for example, analyzing winds, temperature shifts, and chemical processes across varying longitudes and latitudes. These outcomes illustrate how much is left to explore and how each new discovery continues to astonish this rapidly advancing field,” Cont remarked.