NASA, ESA, and E. Wheatley (STScI)
Illustration of the red supergiant star Betelgeuse.
A supergiant red star called Betelgeuse “quite literally blew its top” Nasa says, after a large chunk of its surface blasted off into space.
The conclusion around the unprecedented explosion in 2019 comes after astronomers analyzed data from Nasa’s Hubble Space Telescope and several other observatories.
Although our Sun in our solar system routinely blows off parts of its tenuous outer atmosphere, the corona, in what is called a Coronal Mass Ejection, Betelgeuse blasted off 400 billion times as much mass.
“This is something never before seen in a normal star’s behavior,” Nasa says in a press release.
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Betelgeuse is one of the brightest stars in our night sky. It’s also huge. If the aging star was placed at the center of our solar system for example, it would reach out to the orbit of Jupiter, Nasa’s Hubble website explains.
Betelgeuse’s fate is to one day explode as a supernova, and although it’s showing some unusual behaviours now, Nasa says the star isn’t about to blow up anytime soon.
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“Betelgeuse continues doing some very unusual things right now; the interior is sort of bouncing, ”says Andrea Dupree, a senior astrophysicist at the Harvard-Smithsonian Center for Astrophysics.
“We’ve never before seen a huge mass ejection of the surface of a star,” Dupree explains in the release. “We are left with something going on that we don’t completely understand. It’s a totally new phenomenon that we can observe directly and resolve surface details with Hubble. We’re watching stellar evolution in real time. “
According to the space agency, the star’s ginormous outburst in 2019 was possibly caused by a convective plume bubbling up from deep inside the star. This caused shocks and pulsations that eventually blasted off a chunk of its photosphere (surface). That chunk was believed to weigh several times as much as our Moon, and once it cooled, it formed a dust cloud that blocked light from the star. This dimming in the star’s brightness was visible from Earth at the time, Nasa says.
Following the explosion, scientists also noticed changes in the star’s pulses – it’s pulsation rate disappeared, at least temporarily. For almost 200 years astronomers have measured the star’s rhythm, and the disruption “attests to the ferocity of the blowout,” Nasa says.
Betelgeuse is also still struggling to recover from its injury. Although some of the star’s outer layers appear to be back to normal, its surface is described as “bouncing like a plate of gelatin dessert” as the photosphere rebuilds itself.
Dupree suggests that the star’s interior convection cells, which drive the regular pulsation, may be “sloshing around like an imbalanced washing machine”.
The space agency says that the new observations give clues around how red stars lose mass late in their lives, and how the amount of mass loss significantly affects their fate.