You've heard of a CME, a "coronal mass ejection." They happen all the time. A piece of the sun's tenuous outer atmosphere (corona) blows off and sometimes hits Earth. Something far more terrible just happened to Betegeuse: an SME, or "surface mass ejection."
NASA astronomers believe that in 2019 a colossal piece of Betelgeuse's surface blew off the star. The mass of the SME was 400 billion times greater than a CME. 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.
NASA astronomers believe that in 2019 a colossal piece of Betelgeuse's surface blew off the star. The mass of the SME was 400 billion times greater than a CME. 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.
