by Starlight, bright star, will there be a new star tonight?
That’s the question astronomers are waiting to answer, as they wait for what they believe is a huge explosion in the sky.
To be clear, the star already exists, but is invisible to the unaided eye – yet.
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 red giant star, and the other is a small, but extremely compact, white dwarf.
As they orbit each other, the red giant’s material slips out and falls into the white dwarf where it collects and heat up. Then the white dwarf has a thermonuclear explosion – a nova – brightening to a point where we can see it unaided on Earth.
As material from the red giant accrets around the white dwarf, it gets heated, creating a thermonuclear reaction that makes the white dwarf very bright. (NASA’s Goddard Space Flight Center)
(Interestingly enough, our own sun will eventually become a red giant and then a white dwarf as it nears the end of its life. First it will swell, shedding its outer layers (and yes, destroying all life on Earth ), and then it will be compact and extremely compact, about the size of Earth.)
To understand how bright T Cor Bor will get (as it is known, for short), you need to know how astronomers measure brightness. It’s on a magnitude scale, where – counterintuitively – 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 particular type of variable star is called a recurrent nova.
But the big question hanging in the air is: when? When will T Cor Bor have that great explosion?
Brightening and fading
Astronomer John Birmingham discovered T Cor Bor in the west of Ireland when he went Nova in 1866.
Before that no one understood what caused the stars to periodically brighten and melt.
(CBC News)
But the nova happened again 80 years later, in 1946. Going back, Brad Schaefer, an astronomer and professor emeritus at Louisiana State University who has been studying T Cor Bor for years, gave a long-lost account of white in the same spot. in 1787, suggesting that T Cor Bor is a recurring nova with a period of 79 to 80 years.
Although there were few eyewitness accounts, Schaefer’s work from 1945-47 data shows a rapid drop in the star’s brightness just before the eruption. This is where we are right now, leading Schaefer and others to believe that we’re in for a quick eclipse anytime between now and September.
When it erupts, you must be quick to see it at its brightness.
“T Cor Bór goes from the lowest level, which he is currently struggling with, to his peak [in about] three hours or something like that — it’s very fast,” Schaefer said.
“It’s important that we catch it early because the time it stays at its peak … it’s half a day. It starts to decline almost immediately. So it stays close to the first or second size, where which is visible to the human eye [about] day. So you have a day or two as a chance to see it.”
Only about 10 recurrent novae are known, but the others have much longer timescales. T Cor Bor, with its span of 79 to 80 years, is unique.
“The fact that it’s happening over and over again on a time scale that we could work with, as far as humans are concerned – not thousands of years … but it’s still within a human lifetime – it makes the -special,” said Paul Delaney, an astronomer and professor emeritus at York University’s department of physics and astronomy in Toronto….
The most important thing about this Nova event is that it will be closely monitored by amateurs from all over the world, providing much needed data.
“You have 24-hour coverage because observers are spread all over the world,” Schaefer said. “And so there’s going to be people in Hawaii watching it. There’s going to be people in Japan and even Australia watching it. So, so we have full longitude coverage. But you didn’t have that. back in 1946.”
Don’t be like Leslie Peltier
Who is Leslie Peltier? Well, one might consider him one of the unluckiest astronomers in the world.
This famous comet hunter and fan of variable stars had been carefully watching T Cor Bor for about 25 years, hoping to find it in the eruption phase. The story goes that one morning in February 1946, he set his alarm to wake up at 2:30 am to check on a few stars, including T Cor Bor. But he felt a little under the weather and decided to stay in bed. You can guess what happened: T Cor Bor erupted.
In his book Starlight nightshe wrote (bitterly): “I alone am to blame for being negligent in my duties, nevertheless, I still feel that T. [Cor Bor] it could show me more thought. We had been friends for many years; on thousands of nights I watched him as he slept, and then he got up in my hour of weakness as I nodded at my job. I’m still watching it but now it’s with a wary eye. There’s no heat between us anymore.”
So if you hope to have better luck than Peltier, you need to know what you’re looking for. The best advice is to know the constellation before the eruption.
You can find T Cor Bor in the Corona Borealis constellation, hence its name. The Latin name of the constellation translates to the “northern crown,” because it resembles a crown and is found in the northern sky.
Corona Borealis looks like a squashed “U” in the northern sky between the constellations Hercules and Boötes (Boo-OH-teez). You can easily find Boötes by its brightest star, Arcturus. No other nearby star will be as bright as Arcturus.
Under the dark skies you see the seven brightest stars of Corona Borealis. Alphecca is the brightest at magnitude 2.2. Once T Cor Bor goes nova, it will be almost as bright as Alphecca.
“What I was doing with my daughter is we’re just going out, and we’re trying to find the constellation in the sky. And we’re just looking at what it looks like now,” said Brian Kloppenborg, executive. director of the American Association of Variable Star Observers.
“And just asking questions about, you know, what you see around it like, and then when the actual eruption happens, I’ll probably ask her: do you see new jewels on the crown?”
So, be aware of the night sky and watch every night if you can. You might find that extra crown jewel.
