Hubble is celebrating over three decades orbiting the Earth and taking pictures of beautiful celestial objects scattered around the galaxy. To celebrate its 31st birthday, astronomers aimed Hubble at a star in the Milky Way galaxy called AG Carinae. The star is one of the brightest in the Milky Way, with the brilliance of about 1 million suns. It’s also about 70 times more massive than the sun and burns fuel at an extreme rate.
Consuming so much energy does take a toll on the star, making it prone to expand in size like a hot air balloon and shed outer layers of material into space. The massive halo of glowing gas surrounding the star was created by one or more giant eruptions around 10,000 years ago. NASA says stars like AG Carinae are very rare, with fewer than 50 residing in our local group of galaxies.
AG Carinae is described as waging a tug-of-war tween gravity and radiation to avoid destroying itself. That expanding shell of gas and dust surrounding the star is about five light-years wide, which is about the same distance between the sun and the closest star to us called Proxima Centauri. The amount of material expelled to create that shell of gas and dust is about ten times the mass of our Sun.
Stars of the sort that are the most massive and brightest live for only a few million years compared to the Sun, which can live roughly 10 billion years. AG Carinae is a breed of star called a luminous blue variable. The star is a few million years old and is 20,000 light-years away from us, and is inside the Milky Way galaxy.
Luminous blue variable stars tend to create outbursts such as the one that made its halo of gas and dust once or twice during the star’s lifetime. Material is only cast off the star when it’s in danger of exploding as a supernova.