NASA astronomers have used the Hubble Telescope to photograph one of the brightest stars in our galaxy. This object is surrounded by a halo of gas and dust. Researchers can now see how the star AG Carinae resists gravity and radiation in order to avoid self-destruction.
The expanding shell of gas and dust that surrounds the star is about five light-years across, equal to the distance to the closest star beyond the Sun, Proxima Centauri. It appeared as a result of one or more giant eruptions about 10 thousand years ago. The outer layers of the star will evaporate into space, its weight is 10 times the mass of our Sun.
The researchers added that the flares observed by scientists are typical life of a rare type of star called light blue variables, a phase in the short life of an ultra-bright object that lives quickly and dies young. These stars are among the most massive and brightest known. They live only a few million years, compared to the roughly 10 billion years that our Sun has lived. AG Carinae is now several million years old.
Large flares, which can create a nebula, occur once or twice during the lifetime of a star. A bright blue variable star will only discard material when it is in danger of self-destructing. Because of their massive shape and super-hot temperatures, variable stars like AG Carinae are in a constant struggle to maintain stability.
The researchers noted that this is a competition between pressure from within a star and gravity. This struggle leads to the fact that the star is constantly expanding and contracting. From time to time, external pressure wins and the star expands to its maximum size. But this only happens when the star is on the verge of disintegration.
Like many other blue variable stars, AG Carinae is still unstable.