It's not every night you see a star blow up.
But it will be one of these nights. Some night between now and mid-September.
And if you're the first to see T Coronae Borealis go to blazes — and more importantly, if you're the first one to photograph it — you could make astronomy history.
"We're encouraging as many people as possible to look at it and photograph it," said Gary Swangin, Warren County astronomer-at-large and past director of the Newark Museum Planetarium and the Panther Academy Planetarium in Paterson.
"No one knows the exact time of the outburst," he said. "And when it happens, we'd like a picture of it."
T Coronae Borealis — also known as "The Blaze Star" — is a nova. A word that means "new."
In fact, this explosion is old. It's 3,000 light years away — which means the light took three millennia to reach us. The coming cataclysm, which has stargazers on tenterhooks, actually happened about the time the Phoenician alphabet was invented.
Here's how to find it
How do you find T Coronae Borealis? Not difficult, Swangin said.
You'll need binoculars. Look for the Big Dipper — you know what that looks like, right? Follow the curve of the handle away from the dipper's spoon and "arc to Arcturus" — the first bright star you come to. It's in the constellation Boötes — known for its "kite" formation. "A diamond in the sky," as it were.
To the right of that, you'll see a star formation that looks like a horseshoe — curved part down. That's Coronae Borealis — the Northern Crown. On the left prong of the horseshoe, toward the bottom, is T Coronae Borealis. Just waiting to blow its top.
Right now, you'll need binoculars to see it. But when it goes nova, it will be the jewel in the crown — the brightest star in that group.
When will it blow up? No one can say exactly. Some night between now and Sept. 24, probably.
How long will it last? A day or two, probably.
How do we know it will blow up? Because it blew up the last time.
T Coronae Borealis is what is known as a "recurrent" nova. Like Old Faithful, it erupts on schedule. Its 80-year cycle was observed in 1866, and again in 1946. But on neither occasion did anyone snap a picture.
"Amateur astronomers, citizen scientists, can contribute to the scientific importance of the event," Swangin said. "If you can capture images of the explosion with a telescope, or some other optical device, you might contribute something historic. You might be the first person to photograph this outburst."
Story of a star
Why does this nova keeps on nova-ing? That's a story in itself.
Usually, when we think of novas, we think of a "supernova" — those cataclysmic explosions that lead giant stars to collapse in on themselves. The sheer force of gravity reduces them to pulsars — or in the most extreme cases, black holes.
They were called "novas" because they appeared — to us on Earth — as a new star in the sky. New and terrifying: a unsanctioned star, in a sky that was supposed to be perfect and unchanging, could only mean disaster. The word itself means "bad star." And some novas have been so bright they were visible in the daytime — like the supernova of 1054 A.D., whose gaseous remains can still be seen as the Crab Nebula. Saints preserve us!
Some of the greatest astronomers made their bones by reassuring the public that novas were, in fact, No Big Deal.
Danish astronomer Tycho Brahe proved that the terrifying nova of 1572 was actually a faraway object, well beyond the moon. Frederick II of Denmark was so grateful he gave Tycho his own observatory, Uraniborg: the first in modern Europe. Galileo boldly proclaimed that the supernova of 1604 was not a new star at all, but an old one — normally too faint to be seen — experiencing a flare-up. He predicted it would soon be invisible again. When it was, his fame increased. So did his enemies in the church.
Two to tango
All of these were one-time events. But T Coronae Borealis is a special — and fascinating — case. It's actually a double star: a red giant and a white dwarf. And they have what might be called a toxic relationship.
"It probably scares people if you use the technical name: Mass Transfer," Swangin said. "The white dwarf is pulling material off the red giant."
White dwarfs are small, but dense. Red giants are big, but lighter. The dwarf's heavy gravity pulls material off of the giant and absorbs it into itself. And this goes on and on, until the white dwarf is gorged. "When you get this Mass Transfer, the white dwarf becomes unstable. It wants to blow away that mass. It heats up inside and the thermonuclear reaction causes it to explode. That's what you see as a nova."
Every 80 years, the dwarf star of T Coronae Borealis blows off its outer shell, leaving the core. Then it starts bingeing again. Then it purges. And so on, and on. It sounds odd, but it's not uncommon, Swangin said.
"Since we know that a significant number of stars in the universe belong not only to a binary system but multiple star systems, it's not that unusual to have this take place," he said. "We've seen this in other galaxies."
