Astronomers puzzled over the red giant’s weak phase / expert sees no harbinger of a supernova.
The end of Betelgeuse would be clearly visible from Earth: The dying giant star could then shine as brightly as a full moon. Striking measurements have fueled speculation that the time may come – soon, however, at an astronomical scale.
Astronomers are puzzled about an unusual period of weakness for the Red Giant Betelgeuse in the constellation Orion. The brightness of the giant sun has more than halved since October. The exact cause of the sharp drop in brightness is not known, explained the star researcher Thomas Janka from the Max Planck Institute for Astrophysics in Garching near Munich. The scientist does not see the phenomenon as a sign of an impending supernova explosion of the star, which had been speculated on the Internet.
Betelgeuse forms the shoulder of the sky hunter Orion and is the second brightest star of this constellation. It can be seen with the naked eye as a bright red dot. The giant star has about twenty times the mass and around a thousand times the diameter of our sun. The brightness of the red giant fluctuates in two irregular cycles, each lasting almost six years and approximately 425 days. “We do not know exactly what is the variability of Betelgeuse,” said Janka. Possibly clouds of matter blown from the star into space temporarily swallowed the light of the giant sun.
In December, researchers led by Edward Guinan from Villanova University in the USA reported the lowest brightness of Betelgeuse since the first such measurements were made almost 100 years ago. The striking weak period seems to stem from the fact that both star’s activity cycles would have reached an unusually low minimum at the same time, the researchers wrote in the astronomer’s telegram.
Since Betelgeuse burns its supply extremely quickly, the red giant has a short life expectancy: although it is only about eight million years old, it will soon explode as a supernova. In astronomical terms, however, that means: in the next 100,000 years. Since Betelgeuse is only 600 light-years away, this supernova is estimated to be as bright as the full moon in the earthly sky.
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