Galactic Powerhouse
Hypergiant enigma solved?
With this discovery a crucial 'missing link' in the evolution of hypergiant stars has been found.
A European research team has published the results of a 30-year study of an extraordinary hypergiant star. They have found that the surface temperature of the super-luminous star HR 8752 increased by about 3000 degrees in less than three decades, while it went through an extremely rare stage called the 'Yellow Evolutionary Void'. The discovery marks an important step closer to unravelling the evolution of the most massive stars. A team of astronomers from six European countries, including the Royal Observatory of Belgium (ROB), has investigated the hypergiant star HR 8752 for 30 years while it traversed the 'Yellow Evolutionary Void'. The 'Void' is a short stage in the lives of the most massive stars when they become very unstable. The team finds that the surface temperature of HR 8752 rose surprisingly fast from 5000 to 8000 degrees in less than 30 years. The research results were very recently published in the journal Astronomy and Astrophysics. The discovery is an important step forward to resolve the enigma of the hypergiants, the most luminous and massive stars of the Galaxy. Hypergiants can shine millions of times brighter than the Sun, and they often have a diameter several hundred times greater. HR 8752 is a quarter million times more luminous than the Sun. The powerhouse is therefore visible with normal binoculars at large distance from Earth in the Northern constellation of Cassiopeia. There are currently only 12 hypergiants known in our Galaxy. The 'Yellow Evolutionary Void' is a unique stage in the short life of a hypergiant when its temperature and luminosity can quickly change.
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