A CME, or Coronal Mass Ejection, occurs when part of the Sun’s corona, a plasma atmosphere of a star that happens to be very, very hot, which is required for a plasma, is blown off and outwards, usually by the magnetic forces of the star.
So what’s a Surface Mass Ejection (SME)?
NASA astronomers believe that in 2019 a colossal piece of Betelgeuse’s surface blew off [the red supergiant Betelgeuse]. The mass of the SME was 400 billion times greater than a CME or several times the mass of Earth’s Moon. Data from multiple telescopes, especially Hubble, suggest that a convective plume more than a million miles across bubbled up from deep inside the star, producing shocks and pulsations that blasted a chunk off the surface.
“We’ve never before seen such a huge mass ejection from the surface of a star,” says Andrea Dupree of the Harvard-Smithsonian Center for Astrophysics, who is leading the study. “Something is going on that we don’t completely understand.”
After it left the star, the SME cooled, forming a dark cloud that famously dimmed Betelgeuse in 2019 and 2020. Even casual sky watchers could look up and see the change. Some astronomers worried that the dimming foreshadowed a supernova explosion. The realization that an SME is responsible has at least temporarily calmed those fears. [Spaceweather.com]
Betelgeuse isn’t the biggest star around, but it might be in the top ten, with a diameter so huge that it’s literally greater than the diameter of a Jovian orbit.
Something that size blowing pieces off isn’t even terrifying. If our star did that, we’d probably never even know. We’d just be blotted out, as if the Divine had decided it’d made a mistake with us and was starting over.
It’s maybe 500 light years away, ± some odd numbers that appear to be in dispute, which, for my purposes, means we’re about 4 rows back in the audience if something serious happens to Betelgeuse.
