This distant planet has a comet-like tail 350,000 miles long

Humanity has observed more than 5,500 worlds orbiting other stars, some of which are truly strange. One appears to contain clouds of titanium, while the other, Glass storms It might rain.

WASP-69b, a planet orbiting a star 160 light-years away, is the latest addition to the eccentric menagerie. As revealed this week in American Astronomical Society Meeting In New Orleans, this exoplanet has a 350,000-mile-long tail of helium gas billowing up behind it like a comet.

WASP-69b is slightly larger than Jupiter, although it is considerably less massive, and is so close to its star that one complete orbit takes just 3.9 Earth days. This makes it what astronomers call a hot Jupiter, a common type of exoplanet.

However, its bright tail – 50% longer than the distance between Earth and the Moon – is a far cry from everyday life.

As the star's intense radiation ignites WASP-69b, the planet's atmosphere heats up to about 17,500 degrees Fahrenheit and swells. The planet's outer matter gets caught up in the stellar wind and accelerates through space, eventually reaching speeds of 50,000 miles per hour.

“Most hot Jupiters lose mass this way, but not all of them have tails,” he said. Dakota Tylera doctoral candidate in astrophysics at the University of California, Los Angeles, and author of an accompanying study published this week in Astrophysical Journal. “The only way to get the tail is if you have excessive stellar winds that reshape and sculpt it, basically like a comet.”

He's been there before It is implied that WASP-69b It had a modest-sized helium tail, but scientists were unable to solve the problem Whether it's real.

Determined to find out, Mr. Tyler, Eric Petigura, an exoplanet researcher also at UCLA, and their colleagues headed to the Keck Observatory atop Mauna Kea in Hawaii. They used its abundant starlight scanning capabilities to capture a detailed image of the exoplanet, confirm the presence of the tail and reveal its enormous length.

WASP-69b's planetary feathers are more than just decorative, helping to answer the question on the minds of exoplanet hunters: Where are all the hot planets?

It is clear that among the abundance of alien worlds there are Neptune-sized objects with tight orbits around their host stars. The rarity of hot planets can be explained by their inability to withstand the brutal bombardment of stellar radiation. Hot Jupiters have enough mass and gravity to retain a significant portion of their atmosphere over astronomical timescales. But the gaseous envelopes of hot, relatively diminished Neptunes are thought to be easily blown away, quickly turning them into mini-planetary crusts.

WASP-69b may lose 200,000 tons of mass every second, but even at that rate, it will retain most of its atmosphere for the life of its star. This makes it an ongoing laboratory experiment for astronomers to observe how planets lose mass. “WASP-69b helps us study it in real time,” Dr. Petigura said.

Although its cosmic moon makes WASP-69b stand out among its exoplanetary peers, “we've found other planets with tails,” he said. Jesse Christiansen, a project scientist at NASA's Exoplanet Archive, who was not involved in the new study. Several other hot Jupiters are known to have steaming heads, and Kepler-10b, a rocky world, is so close to its star that its surface evaporates into a band of iron and silicate.

“This process continues, to some extent, with all planets,” Dr. Petigura said.

Since atmospheric mass loss is a global feature, using WASP-69b to better understand it “will allow us to predict how common planets like Earth are,” Dr Christiansen said.

As always, the exoplanetary saga is ultimately the story of our cosmic island.