Revenge of the geek

Astronomers have discovered the biggest, brightest, most massive, most energetic star they have ever found. It's as much as 40 million times brighter than the Sun, at least 150 times as massive and at least 200 times as wide. Next to this star, called LBV 1806-20, the Sun would appear as small as Mercury does next to the Sun.

In fact, it's so big and so bright that the usual theories of how stars form can't explain its existence.

Stars usually form when huge, swirling clouds of hydrogen gas collapse under their own mutual gravity until the center of the gathering mass is squashed so hard that a fusion reaction - where hydrogen atoms fuse with neutrons to form deuterium which in turn fuse to form helium - starts. This reaction releases enormous amounts of energy (think hydrogen bomb and e=mc² to get an idea of the scale) which pushes out against the gravity and heats the ball of gas until it's hot enough to glow. And there's your star.

All well and good and fits observations. But calculations say that a star should be no more than 120 times as massive as the Sun. Any more massive and the energy of the reaction would blow the nascent star apart before it could form. So what gives?

LBV 1806-20's neighbors include some other very massive stars and a neutron star, the extremely dense remainder of the core of a massive star that exploded - a supernova. This suggested a hypothesis that the supernova pushed nearby gas clouds together. That is, the gas clouds that formed LBV 1806-20 and its neighbors didn't just collapse under their own gravity, they were slammed together by the supernova's shockwaves.

Still so much to know....

Footnote: LBV 1806-20 won't be around too long by astronomical standards. The more energetic a star, the faster it goes through its nuclear fuel and the sooner it dies. Our supermassive friend will only be around a few million years. A long time by our standards, but only a tiny part of our Sun's life of some 10 billion years, roughly the equivalent of two weeks versus a century.