Hubble space telescope observes planet bleeding its atmosphere into space

July 28 (UPI) -- The Hubble Space Telescope observed a young planet that is orbiting so close to its parent star that it is spewing its atmosphere into space, NASA said.

The planet orbits the star AU Microscopii, which is 32 light-years away from Earth and the Hubble space telescope was able to detect the planet's atmospheric bleeding by measuring the variability of dips in brightness as the planet moves in front of it.

"A young planet whirling around a petulant red dwarf star is changing in unpredictable ways orbit by orbit. It is so close to its parent state that it experiences a consistent torrential blast of energy, which evaporates its hydrogen atmosphere causing it to puff off the planet," NASA said on Thursday.

The star is only about 100 million years old, which is very young when compared to our own 4.6-billion-year-old sun. The planet observed bleeding mass is only about 6 million miles away from AU Microscopii, about ten times closer to the star than Mercury is to the Sun, and it orbits the star once every 8.46 days.

Like other red dwarf stars, AU Microscopii emits strong radiation and solar flares which could make it harder for planets orbiting similar stars to host life.

The planet was previously observed passing in front of AU Microscopii without showing any signs of bleeding its mass, but observations a year and a half later showed that the planet was bleeding mass.

"We've never seen atmospheric escape go from completely not detectable to very detectable over such a short period when a planet passes in front of its star," said Keighley Rockcliffe of Dartmouth College.

"This frankly strange observation is kind of a stress-test case for the modeling and the physics about planetary evolution. This observation is so cool because we're getting to probe this interplay between the star and the planet that is really at the most extreme," Rockcliffe said.

The planet was first observed in 2020 by NASA's Spitzer space telescope and the Transiting Exoplanet Survey Satellite using the transit method, which observes the dip in brightness caused when a planet passes in front of a star.

Researchers have theorized that the large variations in the atmospheric bleeding could be caused by solar flares, which can result in hydrogen being photoionized to a point where it would become so transparent that it would not be observable.

Alternately, researchers say the variability in atmospheric bleeding could be caused by the variations in solar winds emanating from the red dwarf.