Burning huge, fast and furious, then exploding in the most spectacular way. We just love that, don’t we? Better than our boring sun here, reaching middle-age at 4.5 billion years old, then slowly dying by engulfing our inner planets in the next few billion years, then cooling to a nice big hunk of dark carbon. But that’s not the life for Betelgeuse. Betelgeuse is a star, and not just any star. Betelgeuse is a supergiant — a true superpower. And it’s raging.
Betelgeuse is actually relatively close to us. It’s about 425 light years away, sitting in its place as the upper-left star in the constellation Orion. Like our country, Betelgeuse is very young, probably only about 6 million years old. But it’s already dying. It could happen any day. And it will be spectacular.
Our common, middle-aged sun at 4.5 billion years seems small compared to the 6 million year old Betelgeuse. If Betelgeuse were in the sun’s position, it would be engulf all the inner planets, including Mars, the asteroid belt, and extend past the half-way mark to Jupiter. That’s big. Our fastest crafts take years to travel those distances. Betelgeuse has already burned out its primary source of fuel, hydrogen, and is now fusing helium into oxygen and carbon, which our sun will start doing in about 2.5 billion years. By that time, Betelgeuse will be long dead. But before it goes, unlike our sun, it will continue fusing the atoms of carbon and oxygen into even heavier elements like neon, magnesium, sodium, silicon and even iron. That’s the stuff of our Earth. But it will be a strange and violent death for Betelgeuse, and beautiful for us — because we will see the explosion in our skies, and it will be bright enough to cast shadows in the night, and even be visible by day.
Once Betelgeuse burns out its helium, the rest of the elements will fuse pretty quickly. Once silicon is being formed, it will fuse for less than a day producing iron. Then the big event happens — a supernova. And this could happen any day now. In fact, it may have already blown up a few hundred years ago, but we just haven’t seen it yet. Betelgeuse will suddenly collapse an enormous volume, exploding all the material it has fused into a nebula of matter that will eventually spread across several light years. This is a death, and a birth of all the elements necessary to form planets like our own. In the case of Betelgeuse, it will also be the birth of a very strange, somewhat “undead” object.
The core of the collapsed supergiant will become so dense that electrons will be forced to fuse with protons, creating a strange ball of neutrons — well, for the most part. Betelgeuse, instead of being large enough to burn half of our solar system, at this point will be only a few miles wide. But it is a very bizarre few miles of super density. A teaspoon of this neutron star will weigh about 11 trillion pounds. Quantum superfluid properties will come into play. Gravitational forces are enormous, with the escape velocity from a neutron star being approximately half the speed of light. Any matter whatsoever getting caught in within the gravity of a neutron star will become super accelerated, ripped into its component atoms to become the same substance of the star itself.
Neutron stars rotate very fast, too, some hundreds of times per second. Although mostly neutrons, even stranger properties allow protons to exist toward the center, with electrons on the periphery, very much like one gigantic atom might look. This creates incredibly strong magnetic fields which spin around with the star, ripping atoms apart from surrounding space, and even itself, along the magnetic field lines to be flung into the north and south poles of the star, directed into tight, narrow beams of bright radiation that flash out into space — in other words, a pulsar. The Betelgeuse neutron star may, though, instead become a magnetar.
The strong magnetic fields will slowly cause the spin of Betelgeuse to lessen until it vanishes from sight. However, if this former supergiant manages to pair up with another star, or runs into a good supply of new matter, it can begin stripping the new source bare into its constituent atomic parts, spinning itself back up into its full undead glory as a rejuvenated neutron star.
These are the quintessential rock stars of the universe — or the relentlessly consuming Bear Stearns. The fast, bloated, consuming at all costs supergiants that inevitably blow themselves up, to seed the universe with their debris, and carry on as the much smaller, dense undead, forever needing more.
Image Credit: RCW 103, NASA/CXC/Penn State/G.Garmire et al