Astronomy: Vast gas bubble surrounding a red giant poses a new mystery
A previously unknown gigantic bubble around the red giant DFK 52 points to an explosion 4000 years ago. How it survived this is unclear.
The bubble around DFK 52, red is material moving away from us, blue is material moving towards us.
(Image: ALMA(ESO/NAOJ/NRAO)/M. Siebert et al.)
A research group from Sweden has discovered a gigantic bubble of gas and dust around a red giant star, which must have been created in an explosion 4000 years ago. How the star survived is a mystery, explains Chalmers University of Technology in Gothenburg. The structure around the star, known as DFK 52, stretches 1.4 light years into space and contains as much mass as our sun. How the star was able to hurl so much material into space in a comparatively short time without ending up in a supernova is unclear. It might have a previously undiscovered companion, just like the one recently discovered in the best-known red giant star Betelgeuse.
Supernova in a few hundred thousand years?
The team found the bubble using the ALMA radio telescope network of the European Southern Observatory ESO. The discovery was a "big surprise", explains research leader Mark Siebert. DFK 52 is actually more or less a twin of Betelgeuse, but unlike Betelgeuse it is surrounded by a "huge, chaotic bubble of material". If the star were as close to us as Betelgeuse, the bubble in the night sky would be about a third of the size of the full moon. The research group wants to investigate the star further and find out whether it will end up in the next supernova in the Milky Way. This could happen sometime in the next million years. The team presents the discovery in Astronomy and Astrophysics.
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The structure discovered at DFK 52 is the largest of its kind in the Milky Way, the team adds. Red giant stars like the one at its center have reached the end of their lives and are comparatively close to their final explosion. The very similar Betelgeuse has caused a lot of excitement in recent years after it unexpectedly dimmed considerably. It was sometimes assumed that this supernova was really imminent. In the summer, a research team then announced that they had found a previously undetectable companion star in the shoulder star of the constellation Orion. Its existence had been postulated as an explanation for the dimming only a year ago.
(mho)
