For decades, a nearby star named AU Microscopii has intrigued astronomers as a possible home for planets.
Now, scientists using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and retired Spitzer Space Telescope have discovered a planet about as large as Neptune—one that circles the young star in just over a week.
The new planet, AU Mic b, is just 32 light-years from Earth. It is described in a paper published June 24 in Nature.
“Most exoplanets we know of orbit stars that are billions of years old,” said astrophysicist Emily Gilbert, a graduate student at the University of Chicago and co-author of the paper. “This new discovery is unique because this star is only about 20 million years old, so it allows us to study what happens to planets in the early stages of their lives.”
Still surrounded by a disk of debris left over from its formation, AU Microscopii offers a one-of-kind laboratory for studying how planets and their atmospheres form, evolve and interact with their stars. Known as AU Mic for short, the star lays at the center of a touchstone system, which can help further research into the formation and evolution of stars and planets for decades to come.
“AU Mic is a young, nearby M dwarf star. It’s surrounded by a vast debris disk in which moving clumps of dust have been tracked, and now, thanks to TESS and Spitzer, it has a planet with a direct size measurement,” said co-author Bryson Cale, a doctoral student at George Mason University. “There is no other known system that checks all of these important boxes.”