June 22, 2021

An exoplanet the size of Neptune discovered 32 lightyears from Earth

An exoplanet the size of Neptune has been discovered around the young star AU Microscopii, thanks in part to the work of Jonathan Gagné, a former iREx Banting postdoctoral researcher who is now a scientific advisor at the Rio Tinto Alcan Planetarium.

Astrophysicists have been searching for exoplanets in this system, a unique laboratory for studying planetary formation, for more than a decade. The breakthrough, announced today in Nature, was made possible in part by NASA’s TESS and Spitzer space telescopes.


Located about 32 lightyears from Earth, AU Microscopii, or AU Mic, is a young star between 20 and 30 million years old, which is about 180 times younger than our own Sun. In the 2000s, it was found to still be surrounded by a large disc of debris, a remnant of its formation. Since then, astrophysicists have been actively searching for planets around AU Mic, since it is within such discs of dust and gas that they form.

“AU Mic is a small star, with only about 50 per cent of the Sun’s mass,” said Gagné, who participated in the observations and data processing. 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.”

more at eurakalert.org