The Alma telescope revealed a massive solar flare on the surface of the giant red star Mira.
This type of activity is unexpected for a red giant, and the discovery could help explain how winds from these giant stars influence galactic ecosystems, Chalmers University of Technology reported. The new observations offer the sharpest view of the famous double star, revealing the first surface details of Mira A.
"Alma's vision is so sharp that we can begin to see details on the surface of the star. Part of the stellar surface is not just extremely bright, it also varies in brightness. This must be a giant flare, and we think it's related to a flare which X-ray telescopes observed some years ago," said Wouter Vlemmings, astronomer at Chalmers University of Technology, who led the team.
Red giants begin to lose their outer layers as they die, and this activity releases "smoky" stellar winds that carry heavy elements into space that form new baby stars and planets. Mira is one of the most well-known stars of its kind, and can be seen with the naked eye when at its brightest. It is 420 light-years away, and is part of a binary star system also containing a hot white dwarf.
"Mira is a key system for understanding how stars like our sun reach the end of their lives, and what difference it makes for an elderly star to have a close companion," said Sofia Ramstedt, astronomer at Uppsala University and co-author on the paper.
Our own Sun's activity is powered by magnetic fields, and seeing a flare on Mira A suggests they also have an influence of the red dwarf. The observations also reveal other previously-unknown features of the binary system.
"This is our clearest view yet of gas from Mira A that is falling towards Mira B" says Eamon O'Gorman, astronomer at Chalmers and member of the team.
The findings were published in a recent edition of the journal Astronomy & Astrophysics.