The mystery of Betelgeuse’s darkness has finally been solved

December 2019, astronomers noticed a strange and noticeable bright light Betelgeuse, A bright red star in the constellation Orion. They were shocked by the phenomenon and asked if it was a sign that the star was going to make a supernova. After a few months, the safest explanations were reduced to two: a short-lived cold patch on the south surface of the star (equivalent to a sunspot) or a set of dust that makes the star more blurred for Earth observers. According to this, we now have our answer new paper published in the journal Nature. It’s dust the main culprit, but is associated with brief appearances of a cold spot.

Like John Timmer of Ars reported last year, Betelgeuse is one of the closest massive stars to Earth, about 700 light-years away. It is an old star, which has reached a phase where the bright red glows and expands, with the hot nucleus having poor gravity adhesion only in the outer layers. The star has something like a heartbeat, even if it is very slow and irregular. Over time, the star expands during periods when its surface expands and then shrinks.

One of these cycles is fairly regular, taking more than five years to complete. On top of that the layer is a shorter and more irregular cycle, requiring less than one year and up to 1.5 years. Although they can be easily tracked with ground-based telescopes, these changes will not result in tremendous changes in starlight, which will take into account the changes observed in the event of darkness.

By the end of 2019, when Betelgeuse was so dark, the difference was seen with the naked eye. The darkness continued in its wake, with a 35 percent drop in brightness in mid-February, before it cleared again in April 2020.

The telescopes that pointed at the giant were able to determine — rather than a neat and uniform decline in luminance — the darkness of Betelgeuse. it was distributed irregularly, gives the star a strange, tight shape when viewed from Earth. This raised many questions about what was going on with the giant. Some experts said that because of the size and advanced age of Betelgeuse, it was a sign of a supernova when creating strange behavior.

By mid-2020, astronomers had changed the tone. It was held by a group of international observers Hubble Space Telescope He pointed to Betelgeuse before, during, and after the dark event. Combined with some point observations of the earth, UV data indicated that a large ravine that formed a cloud of dust near the star caused the star to darken.

“With Hubble, we could see that the material was leaving the surface of the star and moving through the atmosphere, before it created dust that caused the star to fade,” he said. said Andrea Dupree, an astronomer at the Harvard-Smithsonian Astrophysics Center who made these observations. He is also the co-author of the new paper.