The red supergiant star known as Betelgeuse is destined to end its life in a grand supernova explosion. But does the star’s recent dimming hint at that impending event, or something else?
Beetlejuice, Beetlejuice, Beetlejuice
If you’re familiar with the constellation Orion, then you’re no doubt familiar with Betelgeuse, often called “Beetlejuice” by astronomy fans. It’s the big red star that acts as the upper-left shoulder joint of the great celestial hunter. It’s so big that if you were to trade it for our sun, it would swallow all the planets and asteroids in our solar system out past Jupiter.
The monster sun normally dims and brightens as it reaches the end of its life cycle, but from October 2019-February 2020, its light was diminished to three times its normal level. Now, using data from the Hubble Space Telescope, which is highly sensitive to ultraviolet light, researchers have determined the cause.
An outburst that hurled stellar material millions of miles from the star cooled, condensing into a giant dust cloud that obscured the star’s light as seen from Earth.
“With Hubble, we see the material as it left the star’s visible surface and moved out through the atmosphere before the dust formed that caused the star to appear to dim,” said lead researcher Andrea Dupree, associate director of The Center for Astrophysics/Harvard & Smithsonian. “We could see the effect of a dense, hot region in the southeast part of the star moving outward.”
“This material was two to four times more luminous than the star’s normal brightness,” she continued. “And then, about a month later, the southern hemisphere of Betelgeuse dimmed conspicuously as the star grew fainter. We think it is possible that a dark cloud resulted from the outflow that Hubble detected. Only Hubble gives us this evidence of what led up to the dimming.”
The Great Fainting
While astronomers expect this kind of violent belching of gas as the star continues to die and eventually collapse in on itself before bursting outward, Dupree isn’t sure that the dimming, now known as “The Great Fainting,” is evidence of such an event. However, Betelgeuse is now dimming again out of sync with its normal brightening and darkening cycle, which would typically have it getting brighter until April 2021.
While more research is needed to figure out what’s now going on with the celebrity star, if we are lucky enough to witness it, a supernova event would appear as a glowing orb that would grow to about the size of the moon and be visible even in the daytime sky. The last time a supernova was visible with the naked eye was 1604.
Because Betelgeuse is about 750 light-years away, the starlight that we see now dates from about 1300, so while we talk about The Great Fainting as a recent event, it’s actually over 700 years old.
The study has been reported in the peer-reviewed Astrophysical Journal.