After a strange phase of darkness, the giant star Betelgeuse found its way back to normal brightness. Some had hoped for a stellar spectacle.
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One of the achievements of modernity is that you can not only follow people on social networks, but also stars. A particularly prominent celestial body has the Twitter name @betelbot. Almost every day the star Betelgeuse tweeted there, which in German is called Betelgeuse due to a historical typing error. It is the left shoulder star of Orion seen from Earth and one of the most striking illuminated signs in the night sky. Now @betelbot has reported that it has regained 100 percent of its former brightness.
This is worth mentioning in that the giant star, a red supergiant with a 700-fold sun diameter, had lost considerable brightness in the past few months. At times his glow had dropped to a third of the normal values. The weakening had led astronomers to speculate: Was Betelgeuse on the verge of an explosion? Would he exhale his star existence as a supernova? It would be a violent spectacle that would be visible to the naked eye for weeks on earth.
Betelgeuse’s last rise would be as bright as the moon seen from Earth. Not only would the light be visible, elementary particles such as neutrinos would also hit the earth in tremendous masses, as would X-rays. This bombardment could largely stop the earth’s magnetic field and air envelope, but chemical changes in the stratosphere would be just as likely as damage to satellites and spacecraft.
But now the spectacle is probably canceled. Celestialists assume that the star, fluffed up to form a gigantic gas ball, wobbles like a cloud of smoke that is heated from the inside. Betelgeuse is almost a billion times the volume of the sun, but is only 20 times as heavy as it is. It is therefore almost a mixture of a star and a gas cloud. So it was presumably dust that floated like gas bubbles in a saucepan from the hot center of the star on its periphery. This also speaks for the fact that Betelgeuse hardly got cooler during its darkening, which can be seen from its light spectrum. If the star had started to inflate, possibly as a prelude to its self-destruction, the light spectra would have to reveal a considerable cooling.
It will take a few thousand years before Betelgeuse dies of natural star death. But then Orion’s shoulder will not burn inconspicuously, but will burst in a huge detonation. The rest of the matter will collapse without the radiation pressure from the hot inside of the star and condense so that a black hole remains. Until then, Betelgeuse is a teaching example in which astrophysicists study how a star of this size ends its existence. @Betelbot continues to tweet the latest developments. Behind it is the American Association of Observers of Variable Stars.
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