WASP-69b: The Jupiter-sized planet with a spectacular comet-like tail

Illustration of planet with tail orbiting a star. Credit: Adam Makarenko/W. M. Keck Observatory.

Imagine a planet so close to its star that it’s literally boiling away into space!

That’s the story of WASP-69b, a gigantic planet about the size of Jupiter, located some 160 light-years away from Earth.

This incredible planet is making waves in the space community for a very unique reason: it has a massive tail trailing behind it, just like a comet.

Published in the Astrophysical Journal, a team of astrophysicists from UCLA has uncovered this fascinating detail.

They found that WASP-69b’s atmosphere is not just escaping into space but is being sculpted into a huge, comet-like tail by the star’s winds.

This tail stretches out for at least 350,000 miles, which is much longer than anything seen before in such planets.

Dakotah Tyler, a UCLA doctoral student and the lead author of the study, explains that while scientists knew the planet was losing some of its atmosphere, they didn’t realize how extensive its tail was until now.

This discovery is significant because it’s seven times longer than the planet itself!

WASP-69b is what scientists call a “hot Jupiter.” These are gas giant planets that orbit very close to their stars, much closer than any planet in our solar system does to the Sun.

For instance, WASP-69b orbits its star in less than four days – a blink of an eye compared to Mercury’s 88-day orbit around our Sun.

The big news here is how the star affects WASP-69b. The star’s radiation is stripping away the planet’s atmosphere, and the stellar winds are shaping this escaping gas into a long, thin tail.

This discovery is crucial for understanding how planets that are very close to their stars change over time.

Erik Petigura, a UCLA professor of physics and astronomy and a co-author of the study, points out that most stars have a planet orbiting closer than Mercury does to our Sun. The erosion of their atmospheres is important in explaining the kinds of planets we see today.

However, in most cases, this atmospheric loss probably happened a long time ago. That makes WASP-69b special because it lets scientists study this process in real time.

Previous observations of WASP-69b, using telescopes in Spain and San Diego County, only hinted at a tail. But the latest research, using a much larger telescope at the W. M. Keck Observatory in Hawaii, revealed much more.

The team found that the planet’s escaping gas, mostly hydrogen and helium, is being pushed towards Earth by the star’s radiation and winds.

Understanding this comet-like tail is important. It forms when the planet’s escaping atmosphere hits the stellar wind, allowing scientists to study these interactions closely. This research is a big step in understanding how planets and their stars interact with each other.

And here’s an uplifting bit of information: despite losing a massive 200,000 tons of atmosphere per second, WASP-69b isn’t in danger of completely evaporating anytime soon. With a mass about 90 times that of Earth, it has enough material to withstand this loss over its lifetime.

Tyler likens the resilience of WASP-69b to the challenges we face in life, reminding us that our capacity to endure and overcome is often greater than we think.

The study also includes contributions from Antonija Oklopcic of the University of Amsterdam and Trevor David of the Flatiron Institute, adding to this exciting chapter in our exploration of the universe.