An unexpected observation of a neighbouring planet whose atmosphere is being destroyed by violent outbursts from its star was made by the Hubble Space Telescope.
Since Hubble last examined the planetary system and found nothing irregular, a lot has changed.
The red dwarf star known as AU Microscopii, or AU Mic, is situated 32 light-years from Earth, which is rather close astronomically, but still outside our solar system.
The star is less than 100 million years old, just a tiny portion of the age of our 4.6 billion-year-old Sun, and it supports one of the youngest planet systems yet discovered.
During studies in 2020, the now-retired Nasa Spitzer Space Telescope and the Transiting Exoplanet Survey Satellite found the system. A modest decrease in the star’s brightness indicated the presence of a gaseous planet circling in front of it.
Hubble did not notice anything during the first orbit, but an orbit two-years-and-a-half years later revealed that the closest planet was being violently destroyed by the star’s radiation, which was vaporising its hydrogen atmosphere.
The Astronomical Journal will publish the findings.
Study author Keighley Rockcliffe, a doctoral candidate in physics and astronomy at Dartmouth College in Hanover, New Hampshire, said in a statement:
“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.
“We were really expecting something very predictable, repeatable. But it turned out to be weird. When I first saw this, I thought, ‘That can’t be right.’”
In the red dwarf system, astronomers are also investigating and seeking potentially habitable worlds.
Ms Rockcliffe added: “We want to find out what kinds of planets can survive these environments. What will they finally look like when the star settles down? And would there be any chance of habitability eventually, or will they wind up just being scorched planets?”
