Betelgeuse first came to attention in late 2019 with an unexpected dimming of the red gem-like star in Orion’s upper right shoulder. The super giant continued to weaken in 2020.
Some scientists hypothesized that the star would explode as a supernova and have been trying to figure out what happened to it ever since.
Now, astronomers have analyzed data from the Hubble Space Telescope and other observatories, and they believe the star has undergone a titanic surface mass ejection, losing a significant portion of its visible surface.
“We’ve never seen a massive mass ejection from the surface of a star before. We’re dealing with something we don’t fully understand,” said Andrea Dupree, an astrophysicist at the Center for Astrophysics | Harvard and Smithsonian in Cambridge, Massachusetts, in a statement.
“With Hubble, it’s a completely new phenomenon that we can directly observe and resolve surface details. We’re watching the evolution of stars in real time.”
Our Sun regularly experiences coronal mass ejections, in which the star releases parts of its outer atmosphere known as the corona. If this space weather hits Earth, it could affect satellite-based communications and power grids.
But Betelgeuse’s surface mass ejection was unleashed 400 billion times the mass of a typical coronal mass ejection from the Sun.
The life of a star
Observing Betelgeuse and its unusual behavior has allowed astronomers to track what happens at the end of a star’s life.
As Betelgeuse burned through the fuel in its core, it swelled to enormous size and became a red supergiant. The giant star is 1 billion miles (1.6 billion kilometers) in diameter.
Eventually, the star will explode in a supernova, an event that can be seen briefly on Earth during the day. Meanwhile, the star experiences some fiery angry tantrums.
The amount of mass stars lose when they burn up during nuclear fusion can affect their survival. But even losing a significant portion of its surface mass is not a sign that Betelgeuse is ready to explode, according to astronomers.
Astronomers like Dupree studied how the star behaved before, during, and after the eruption. to understand what happened.
Scientists believe the convective plume, more than 1 million miles (1.6 million kilometers) wide, originated inside the star. The plume stripped off part of the star’s outer shell, called the photosphere, creating shocks and pulsations that triggered the eruption.
A piece of Betelgeuse’s photosphere, which is several times heavier than the Moon, has been released into space. As the mass cooled, it formed a large cloud of dust that blocked the star’s light when viewed through telescopes on Earth.
Betelgeuse is one of the brightest stars in the Earth’s night sky, so it was observed to dim for several months. observatories and backyard telescopes.
Blast recovery
Astronomers have measured Betelgeuse’s rhythm for 200 years. This star’s pulse is essentially a cycle of dimming and brightening that restarts every 400 days. This pulse has stopped for now – proving how effective the eruption was.
Dupree believes that the internal convection cells that cause the star to pulsate are still reverberating from the explosion, which he likens to the rattling of an unbalanced washing machine tub.
Telescope history Betelgeuse showed that the star’s outer layer normalized as it slowly recovered, but its surface remained springy as the photosphere rebuilt.
“Betelgeuse continues to do very unusual things right now,” Dupree said. “The interior kind of jumps out.”
Astronomers have never seen a star lose so much of its visible surface before, suggesting that surface mass ejection and coronal mass ejection may be two very different things.
Researchers will have more follow-up chances to observe the mass ejected from the star using the James Webb Space Telescope, which could reveal additional clues through otherwise invisible infrared light.
