Betelgeuse supernova: Mysterious dimming could mean one of the brightest stars is about to explode, say scientists
Astronomers knew that Betelgeuse was nearing its end as huge stars like Betelgeuse, which is only about 8.5 million years old, live fast and die violently
Betelgeuse, a giant orange star in the Orion constellation, was once known for its brightness. However, the giant has been losing its trademark sheen, leading astronomers to speculate that the star could be nearing its end.
Until recently, Betelgeuse was ranked among the 10 brightest stars. Cut to December, the star has slipped places and lost its position even among the top 20 stars, writes Edward Guinan from Villanova University in an article in Astronomer’s Telegram.
“Now the outline of Orion is noticeably different with Betelgeuse so faint,” Guinan tells National Geographic.
However, it is not unusual for Betelgeuse to dim. It is a variable star, which means it shows a periodic increase and decrease in brightness. However, the manner in which the star has faded this time has raised eyebrows. The star is the dimmest it has been since more precise monitoring began around a century ago, says Guinan.
The change is so noticeable that scientists are wondering whether the star is going supernova, exploding and burning brighter than our moon, before disappearing from the night sky.
“As massive stars near the end of their lives, they experience insane and violent mass loss. In theory, all that ejected dust could shroud and darken the nearly dead star, causing it to dim from our perspective right before it goes supernova," UC Berkeley’s Sarafina Nance told National Geographic.
Astronomers already knew that Betelgeuse is nearing its end. Huge stars like Betelgeuse, which is only about 8.5 million years old, live fast and die violently. "Stars in the later phases of their life go through a lot of variabilities that we can't fully explain yet. It probably still has tens of thousands of years, if not 100,000 (left)," astronomer Yvette Cendes of the Harvard-Smithsonian Center for Astrophysics wrote on Reddit.
Scientists have not ruled out another theory that might explain why the star is dimming. Guinan says that the star’s current state may be down to its variability in brightness: it fluctuates over two cycles, six-year and 425-day cycles. An overlap of these cycles could be dimming the star and it might continue to fade for another couple of weeks before gradually turning back on, he adds.
But, “if it keeps getting fainter, then all bets are off,” Guinan tells National Geographic.
When it does explode, Earth is not going to be in harm's way, as the star is hundreds of lightyears from Earth, say experts. Also, there is a possibility that the star has already exploded. We are observing the star as it was 600 years ago, as the light from the star takes 600 years to reach us, say experts. If an explosion is spotted now, it could mean that the star actually blew up sometime during the European Middle Ages, and light from the blast is reaching Earth now, say scientists.
Astronomers plan to keep an eye on the star. “This will inevitably yield cool and interesting ideas for what happens to stars right before they explode,” says Nance.