Betelgeuse is what astronomers call supergiant stars. Not so far from the hypergiant category. And a few months ago, they thought they were in the front row of his end of life. Lack. So they turned to a real hypergiant star, “a Betelgeuse on steroids”to try to unravel the mysteries of the death of these stellar monsters.
Remember. It was late 2019, early 2020. Betelgeuse, one of the brightest stars of our sky, had dramatically lost its brightnesswithout the astronomers understand why. They once thought we were about to witness the death of the supergiant star. At the beginning of its explosion in supernova. But it was not. Betelgeuse has finally regained its luster.
And the supergiant stars have continued to keep part of the secret, which researchers at the University of Arizona (United States) hope to lift thanks to a three-dimensional image of a star that is not supergiant, but indeed hypergiant. An image that reveals the processes that accompany the death of these extraordinary objects.
Of hypergiant stars, there are only a few. Only a few in the vastness of our Milky Way. V.Y. Canis Majoris (VY CMa) is one of them. As its name suggests, it is located in the constellation of Grand Dogto just over 3,000 light years of our Earth. Its diameter is about 10 to 15,000 times the Earth-Sun distance. It could be the bulkiest star in the Milky Way. “Like a Betelgeuse under steroids »comments Lucy Ziurys, researcher, in a statement from the university of arizona.
No supernova for hypergiant stars?
It is these extraordinary characteristics that have prompted astronomers to look into the case of V.Y. Canis Majoris. With the aim of verifying whether these star monsters actually evolve into supernovae. “If that were the case, we should see a lot more supernovae in the sky”, says Lucy Ziurys. That’s why researchers think at least some of them might just quietly collapse into black holes.
Unlike less massive stars, hypergiant stars tend to experience loss of masssubstantial and sporadic which form complex and very irregular structures. Kinds of arches, tufts or knots . To learn a little more about VY CMa and how she loses mass – this had been confirmed by observations of the Hubble Space Telescope in particular -, the astronomers traced, thanks to the data of the Large array of millimeter/submillimeter antennas of the Atacama (Chile), certain molecules – the dioxide of sulfur (NA2), silicon oxide (SiO) or even sodium chloride (NaCl) – ejected from the surface of the star. By moving Alma’s antennas, they were even able to obtain very detailed information on the directions and gearsmovement of these molecules.
The researchers then superimposed the whole thing on pre-existing images of the dust surrounding V.Y. Canis Majoris. And what they observed, it is indeed not a loss of symmetrical mass, but many cells of convection. Like giant balls ejected in different directions. “A bit like the coronal arcs that we observe on our Sun. But a billion times bigger”concludes Lucy Ziurys.
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