You may see it lighting up the northern sky in the coming months.
There, in Corona Borealis Over 2,500 light years awayThere lurks a star called T Corona Borealis that could explode and briefly become one of the brightest objects in the night sky.
Astronomers are eagerly awaiting the explosion, hoping that not only will it be spectacular, but it will also provide a wealth of data about a type of stellar explosion known as a supernova. Classical Nova.
We know that T Corona Borealis (T CrB for short) will erupt because it has been doing so once every 80 years for at least eight centuries.
This means that this is very close to being a once-in-a-lifetime event, and that the technology we have now to observe this is far better than it was when we last saw it in February 1946.
“Although there are some novae that repeat on very short cycles, repeated outbursts are not common in a typical human lifetime, and they are rare in the relative closeness to our solar system.” Astronomer Rebecca Hounsell says: of NASA’s Goddard Space Flight Center.
“I’m really excited to have a front row seat.”
Not to be confused with the massive explosion known as a supernova, in which a star is nearly destroyed, a classical nova is a smaller-scale explosion that leaves the star more or less intact. In fact, this is not the first time that this particular space object has had this experience.
The reason T CrB explodes so repeatedly and predictably is due to an anomaly in the type of star it is: a binary system containing the collapsed core remnant of a Sun-like star, called a white dwarf, and a bloated red giant companion star.
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White dwarfs are very small (between the size of the Earth and the Moon) and very dense – 1.4 times the mass of the Sun packed into their volume – which means their gravity is very strong, and if they have a binary companion star in their orbit, it tends to suck up material from it, mainly hydrogen.
Over time, this hydrogen builds up on the white dwarf’s surface and is compressed by gravity. Eventually, the pressure and heat in the bottommost layer of hydrogen becomes so great that the whole thing ignites in a runaway thermonuclear explosion, violently ejecting the excess hydrogen into space in spectacular style.
That’s a nova. For T CrB, this process takes about 80 years.
Over the past decade, astronomers have Observed a double star system This shows similar behavior to that leading up to the 1946 explosion, specifically: Reduced brightness This signals an imminent eruption, which their analysis says could happen as soon as possible, possibly before September 2024.
This means that astronomers are closely watching a small patch of sky packed with constellations like Lyra, Hercules, and Boötes, and a small arc of stars sandwiched between them: Corona Borealis.
The nova will likely be reported soon after it occurs, as it will shine in the sky and become visible to the naked eye, then fade over the course of a week, so there should be time to get out and observe it if you’re interested.
In fact, that would be great: Citizen scientists are being asked to gather data, and the more people who pay attention to T CrB, the better we’ll be able to understand its spectacular explosion phenomenon.
And of course, as many telescopes as possible will be tuned, from the longest radio wavelengths to the most powerful X-rays and gamma rays.
“Recurrent novas are unpredictable and paradoxical” Astrophysicist Koji Mukai says: “You think there could be no reason for it to follow a certain pattern, and yet it does,” said researchers at NASA’s Goddard Space Flight Center. “And just as soon as you start expecting it to repeat, it quickly deviates completely. We’ll have to wait and see how T CrB behaves.”