Humanity has monitored more than 5,500 worlds orbiting other stars, some of which are truly exotic. One appears to have a cloud of titanium, while another has a glass storm It might rain.
WASP-69b, a planet orbiting a star 160 light-years away, is the latest addition to this bizarre zoo. As revealed this week, American Astronomical Society meeting This New Orleans exoplanet has a 350,000-mile-long tail of helium gas trailing behind it like a comet.
WASP-69b is slightly larger than Jupiter, but much less dense and so close to its star that it takes just 3.9 Earth days to complete one orbit. That makes it a common type of exoplanet that astronomers call a hot Jupiter.
But its ornate tail, which is 50 percent longer than the distance between Earth and the Moon, is far from commonplace.
As the star’s intense radiation scorches WASP-69b, the planet’s atmosphere heats up to about 17,500 degrees Fahrenheit and swells. The planet’s outermost material is caught in stellar winds and accelerated into space, eventually reaching speeds of 50,000 miles per hour.
“Most hot Jupiters lose mass in this way, but not all hot Jupiters have tails,” he said. dakota tylera doctoral candidate in astrophysics at the University of California, Los Angeles, and author of a companion study published this week. astrophysical journal. “The only way you can get a tail is if you have excessive stellar winds that basically reshape and sculpt it like a comet.”
It happened before suggests WASP-69b There was a moderately sized helium tail, but scientists couldn’t figure it out. whether it was true or not.
I decided to check it out, Tyler. Eric PettigraHe and his colleagues, also an exoplanet researcher at UCLA, turned their attention to the Keck Observatory atop Hawaii’s Mauna Kea volcano. They used its rich starlight scanning capabilities to take detailed portraits of the exoplanet, confirming the existence of the tail and revealing its extraordinary length.
WASP-69b’s planetary feathers aren’t just for decoration, they help answer a question on the minds of exoplanet hunters: “Where is hot Neptune?”
Conspicuously missing from the otherworldly treasure trove are Neptune-sized objects that orbit in tight orbits around their host stars. The lack of hot Neptunes may be explained by their inability to withstand the onslaught of stellar radiation. Hot Jupiter has enough mass and gravity to retain much of its atmosphere over astronomical timescales. However, it is thought that Neptune’s relatively small and hot gaseous outer shell could easily be blown away and quickly turn into a small planetary shell.
WASP-69b could be shedding 200,000 tons of mass per second, but even at that rate it would retain much of its atmosphere throughout the star’s life. This requires continuous experiments for astronomers to monitor how planets lose mass. “WASP-69b lends itself to real-time research,” Dr. Pettigra said.
Although WASP-69b is notable among the exoplanet family because of its cosmic caboose, “we’ve discovered other planets with tails,” he said. Jesse Christiansen, a project scientist at NASA’s Exoplanet Archive, was not involved in the new research. Several other hot Jupiters are known to have vaporous capes, and the rocky region Kepler-10b is so close to its star that its surface evaporates into streaks of iron and silicates. It has become.
“This process is underway to some degree on all planets,” Dr. Pettigula says.
Atmospheric mass loss is a universal feature, so using WASP-69b to better understand it will allow us to predict how common Earth-like planets will be. ” said Dr. Christiansen.
As always, the story of exoplanets is ultimately the story of our own cosmic island.