An exoplanet the size of Neptune has been discovered orbiting a young star which, astronomers say, is relatively close to Earth.
AU Mic b is around 32 light years away and orbits its host star, AU Microscopii (AU Mic), in the constellation of Microscopium.
Astronomers say AU Mic is 20 or 30 million years old, 150 times younger than the Sun.
Scientists believe that studying this relatively new star system is a “unique laboratory for studying planetary formation” and could help shed light on how our own Solar System formed.
Bryson Cale, a doctoral student at George Mason university and co-author of the study, said: “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... it has a planet with a direct size measurement.
“There is no other known system that checks all of these important boxes.”
The scientists discovered the planet using Nasa's Transiting Exoplanet Survey Satellite (TESS) and the retired Spitzer Space Telescope.
AU Mic b is very close to its star, completing an orbit every 8.5 day, and as a gassy planet weighs less than 58 times Earth’s mass.
Jonathan Gagne, a scientific adviser at the Rio Tinto Alcan Planetarium in Montreal, Canada, who is also an author on the study, said: “AU Mic is a small star, with only about 50% of the Sun’s mass.
“These stars generally have very strong magnetic fields, which make them very active.
“That explains in part why it took nearly 15 years to detect the exoplanet, called AU Mic b.
“The numerous spots and eruptions on the surface of AU Mic hampered its detection, which was already complicated by the presence of the disc.”
