The star AG Carinae is about 70 times the mass of the Sun, surrounded by a dusty shell up to 5 light years wide.
The Hubble Space Telescope took photos of AG Carinae, a blue variable star (LBV) type star, on its 31st anniversary of operation, Space reported on April 23. Around the star is a giant shell of gas and dust five light years wide, about the same distance from Earth to the nearest star without the Sun, Alpha Centauri.
A shell of gas and dust formed when one or more powerful eruptions took place around 10,000 years ago and sent the star’s outer layers into space. This amount of matter is 10 times the mass of the Sun.
“I like to study this type of stars because I am interested in their instability. Their behavior is very strange”, explained Kerstin Weis, researcher on blue variant stars at the University of the Ruhr (Germany).
In the new image, nitrogen and hydrogen gas are red, while the blue area shows the dusty structures that AG Carinae illuminates. Hubble follows the star in visible and ultraviolet light.
The blue variable star has two modes, alternating between stillness and eruption. During the eruption, they become much brighter. Scientists now estimate that AG Carinae is about a million times brighter than the Sun.
The flares actually prevent the star from disintegrating, according to the European Space Agency (ESA). With a star, the internal gravity pressure and the external radiation pressure are generally balanced. But with one unstable star, sometimes one pressure will outweigh the other. In AG Carinae’s case, external pressure briefly overcomes gravity, causing matter to be thrown into space. The eruption brought the star back to equilibrium.
However, massive stars are only resistant to a certain number of such eruptions, after which they run out of fuel. Experts estimate that AG Carinae is 70 times the mass of the Sun and could last 5 or 6 million years.