Starlight, star bright, will there be a new star tonight?
That's the question astronomers are waiting to answer as they await a spectacular stellar explosion they believe is on the horizon.
To be clear: the star already exists, but is invisible to the naked eye for the time being.
About 3,000 light-years away is a binary star system in the constellation Corona Borealis. As the name suggests, a binary star system consists of two stars. In this case, one is a large red giant star and the other is a small but incredibly dense white dwarf.
As they orbit each other, the material is shed from the red giant and falls into the white dwarf where it accumulates andwarms up. The white dwarf then experiences a thermonuclear explosion - a nova - which brightens to a point where we can see it with the naked eye on Earth.
As material from the red giant gathers around the white dwarf, it is heated, causing a thermonuclear reaction that causes the white dwarf to brighten significantly. (NASA's Goddard Space Flight Center)
(Interestingly, our own Sun will eventually become both a red giant and a white dwarf as it nears the end of its life. First it will swell, shed its outer layers (and yes, destroy all life on Earth), and then become compact and super dense, about the size of the Earth.)
To get an idea of how bright T Cor Bor (as it is known for short) will become, you need to know how astronomers measure its brightness. It's on a magnitude scale, where - counter-intuitively - the lower the number, the brighter the object.
T Cor Bor normally shines at magnitude 10. However, it is believed to shine as brightly as a second magnitude star.
When a star changes brightness over time, astronomers call it a variable star. This specific type of variable star is called a recurring nova.
But the big question hanging in the air is: when? When will T Cor Bor experience that beautiful explosion?
The story continues
Brightening and blurringT Cor Bor was discovered by astronomer John Birmingham in western Ireland when it went nova in 1866.
Before that, no one understood what caused the periodic brightening and fading of some stars.
(CBC News)
But the nova occurred again 80 years later, in 1946. Brad Schaefer, an astronomer and professor emeritus at Louisiana State University who has studied T Cor Bor for decades, recently noted a long-lost account of a brightening at the same location. in 1787, which suggested that T Cor Bor is a recurring nova with a period of 79 to 80 years.
Although there are few eyewitness accounts, Schaefer's work from the 1945-47 data shows a rapid decline in the star's brightness just before the outburst. This is where we currently find ourselves, leading Schaefer and others to believe we are headed for a rapid clearing between now and September.
Once it erupts, you'll have to be quick to see it at its brightest.
"T Cor Bor goes from the lowest level, through which it is only just now strolling, to its peak [in about] three hours or something like that - it's really fast," Schaefer said.
"It's important that we catch it early because the time it stays at its peak... it lasts half a day. It starts to fade almost immediately. So it stays near first magnitude or second magnitude, where it is easily visible to the human eye. [about] one day. So you have a day or two to see it."
Only about ten recurring novas are known, but the others have much longer time scales. T Cor Bor is unique with its term of 79 to 80 years.
"The fact that it repeats on a time scale that we could work with, as far as humans are concerned - not thousands of years... but it still happens within a human lifetime - makes it very special," says Paul Delaney, astronomer and professor emeritus at the University of California. The Department of Physics and Astronomy at York University in Toronto.
The great thing about this nova event is that amateurs from all over the world will be watching it closely and providing much-needed data.
"You have 24-hour coverage because you have observers spread across all longitudes around the Earth," Schaefer said. "And so there will be people in Hawaii who will watch it. There will be people in Japan and even Australia who will watch it. So we have full longitude coverage. But you didn't have that." back in 1946."
Don't be like Leslie PeltierWho is Leslie Peltier? Well, you could consider him one of the unluckiest astronomers in the world.
This famous comet hunter and fan of variable stars had been keeping a close eye on T Cor Bor for about 25 years, hoping to catch it during its outburst phase. The story goes that one morning in February 1946, he set his alarm to wake up at 2:30 a.m. to look at some stars, including T Cor Bor. But he felt a little sick and decided to stay in bed. You can guess what happened: T Cor Bor erupted.
In his book Starlight nightshe wrote (somewhat bitterly): "I alone am responsible for being negligent in my duties, nevertheless I still feel that T [Cor Bor] could have paid me more attention. We had been friends for years; a thousand nights I had watched over it while it slept, and then it arose in my hour of weakness when I nodded to my post. I still look at it, but now it's with a cautious eye. There is no more warmth between us."
So if you're hoping to have better luck than Peltier, you need to know what you're looking for. The best advice is to familiarize yourself with the constellation before the outburst.
You will find T Cor Bor in the constellation Corona Borealis, hence the name. The constellation's Latin name translates to the 'northern crown' because it resembles a crown and can be found in the northern sky.
Corona Borealis looks like a squashed "U" in the northern sky between the constellations Hercules and Boötes (pronounced Boo-OH-teez). You can easily find Boötes on the brightest star, Arcturus. There will be no other star around as bright as Arcturus.
Under a dark sky you can see the seven brightest stars of Corona Borealis. The brightest is Alphecca, with a magnitude of about 2.2. Once T Cor Bor goes nova, it will be almost as bright as Alphecca.
"What I've done with my daughter is we just go out and try to find the constellation in the sky. And we just look at what it looks like right now," said Brian Kloppenborg, executive director of the American Association of Variable Star Observers.
"And I just ask questions about, you know, what do you see around it, and then when the eruption actually happens, I'll probably ask her, do you see a new jewel in the crown?"
So familiarize yourself with the night sky and take a look every evening if you can. You might just catch that extra crown jewel.
