NASA telescope discovers cause of mysterious Betelgeuse gradation

in the Before the times, when the Coronavirus pandemic was only just beginning its dark march through the world, our problems were much further away. About 640 light years away, in fact. Astronomers observing Betelgeuse, a red super giant star, had been intrigued by his mysterious gradation. Some believed the event, which lasted from November 2019 to February 2020, was an omen of doom signaling the star’s next explosion. then the gradation stopped abruptly.

Thanks to observations from NASA’s Hubble Telescope, we might find out why.

A new study, published Thursday in The Astrophysical Journal (and available at arXiv), examined the ultraviolet light emitted by Betelgeuse during the “Great Dimming” event using the The Hubble Space Telescope. Fortunately, the event happened just as scientists at Hubble were looking to observe Betelgeuse with the telescope, which shed light on why the star had started to darken.

Betelgeuse is a massive star, about 700 times the size of our sun. If you threw it into our solar system it would swallow Mercury, Venus, Earth, Mars, the different worlds of the asteroid belt together and Jupiter would also end up as a snack. And it’s coming to the end of its life cycle, over the next 100,000 years. When the supergiant began to darken last year, some believers believed the explosion process may have started.

Hubble’s observations suggest differently. By examining Betelgeuse at UV wavelengths, the researchers were able to better see the star’s surface and atmosphere. They discovered a mass of bright, hot material moving outward from the star’s southern hemisphere at around 200,000 miles per hour and eventually ejected into space.

“This material was two to four times brighter than the star’s normal brightness,” Andrea Dupree, associate director of the Harvard-Smithsonian Center for Astrophysics and lead author of the study, said in a NASA statement. About a month after the explosion, the southern part of Betelgeuse visibly darkened, she said.

Dupree and his team believe this material may have started to cool as it moved through space, forming a dense cloud of dust that partially obscured Betelgeuse. It turns out that Earth was in the perfect position to “see” the dust cloud front, as if Betelgeuse had pulled the dust cloud directly at us. If that happened on the other side of Betelgeuse, we probably would never know.

Explosive explosions are expected from stars at the end of their life and when they die or “become supernova” they release a shock wave that spits elements into space. Activity is essential to fill space with heavy elements like carbon, which can then become new stars elsewhere in the universe, so these stars are essential to the cosmic circle of life.

But Betelgeuse always acts a little weird. Observations from NASA’s Stereo spacecraft observed the supergiant between late June and early August and noticed that Betelgeuse was unexpectedly decreasing again. NASA notes that new observations will be undertaken at the end of August, when the star returns to the night sky and can again be seen by telescopes.