Is one of the brightest stars in the sky about to go supernova?

An artist’s impression of the supergiant star Betelgeuse. ESO/L. Calçada

In the corner of the constellation of Orion sits one of the brightest stars in the sky — Alpha Orionis, aka Betelgeuse. Astronomers think that dramatic events could be stirring in this system, with Betelgeuse ready to explode in an enormous supernova.

Consideration of a possible supernova event has been growing following a report by Universe Today and a recent paper by researchers at Villanova University showing the light from Betelgeuse had faded to around half of its usual magnitude. This is a strong indication — though by no means definitive proof — that the star could go supernova soon.

Since that first paper was released earlier this month, speculation has been rife in the astronomical community about if and when Betelgeuse will explode. The researchers of the paper even posted an update just before Christmas that the dimming of the star has contained.

“At its average maximum brightness, Betelgeuse is the sixth or seventh brightest star,” Edward Guinan and colleagues said in the paper. “But by 2019 mid-December the star has slipped to the approximately 21st brightest star… This appears to be the faintest the star has been measured since photoelectric observations have been carried out.”

Although variable stars like Betelgeuse do typically fluctuate in brightness over time, it is the degree of dimming which suggests something may be up with the star at this time. As a star reaches the end of its life, it runs out of fuel and loses a large proportion of its mass. The dying star is surrounded by a halo of dust and gas, obscuring our view of it and making it appear dimmer.

Astronomers know that Betelgeuse is nearing the end of its life, and have been watching it for signs of an impending supernova. When it does blow, the burst of light will be so bright that it will be visible from Earth even during daylight. However, light from the star takes 600 years to reach us, so we’re actually looking back in time and waiting for an event that may have already happened.

Betelgeuse was imaged by the European Southern Observatory in 2009, when observations using the Very Large Telescope revealed the supergiant star was surrounded by a huge plume of gas which is nearly as big as our solar system.

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