Using the ALMA telescope in Chile, researchers from the Chalmers University of Technology have detected what appears to be a gigantic flare on the surface of one of the closest, most well known red giants in the universe – the red giant Mira.
As they explained recently in the journal Astronomy & Astrophysics, ALMA not only allowed them to see the two stars in the system, Mira A and Mira B, in greater detail than ever before, it also revealed surprising activity similar to that observed on the sun when it emits solar flares.
These observations may help them explain how winds from giant stars contribute to the overall ecosystem of our galaxy, lead author and Chalmers University astronomer Wouter Vlemmings, co-author and Uppsala University astronomer Sofia Ramstedt and their colleagues explained.
Why is this important?
Due to ALMA’s incredible capabilities, Vlemmings said that he and his fellow researchers were able to view details on the star’s surface, and they noticed a very bright region that varies in luminosity. They have concluded that this must be a giant flare, and they believe it is related to another flare observed several years ago by X-ray telescopes.
Red giants, the study authors explained, are critical parts of the galactic ecosystem. As they start dying, they begin losing their outer layers in the form of smoke-like winds that carry heavy elements out into other parts of the universe. These elements can form new celestial objects.
Mira is one of the brightest variable stars in the sky and can be seen with the naked eye when it is at its brightest. The star, located 420 light years away in the Cetus, is actually a binary system comprised of two stars of similar mass (one a red giant and the other a white dwarf) orbiting each other at much the same distance that Pluto orbits the sun.
Ramstedt called Mira “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,” and Vlemmings added that observing a flare on the system’s red giant “suggests that magnetic fields also have a role to play for red giants’ winds,” just as they do with solar wind.