Could a new 'star' shine above Kentucky soon? Why NASA is excited again about T Coronae Borealis

Yahoo

06-05-2025

Astronomers have been waiting patiently for months for light from a distant explosion to reach Earth, and the wait might finally pay off, according to NASA.
Scientists alerted the public last year about T Coronae Borealis, a binary star system that could go nova "any day now," experts said. Light from the nova's stellar explosion will make it seem as if a new star is shining in the night sky, though it won't stick around for long.
While stargazers may have been disappointed the nova didn't shine bright in 2024, excitement has been growing recently, according to a May skywatching guide issued by NASA, after astronomers noticed T Coronae Borealis (AKA, T-Cor) suddenly dimmed, which is what happened before its previous nova in 1946.
Here's what we know about T Coronae Borealis, dubbed the "Blaze Star," and why this nova is considered a "once-in-a-lifetime" event.
Story continues after photo gallery.
When can people see a rare nova explosion in 2025?
Roughly anytime now, experts said, though the exact date isn't known. According to an article written last year by NASA, researchers believed T Coronae Borealis could go nova starting in September 2024.
"We hope that it happens any day now," said Dr. Rebekah Hounsell, an assistant research scientist specializing in nova events at NASA's Goddard Space Flight Center in an earlier article. Hounsell cautioned that the exact date is impossible to pin down. "The timing of when it does happen is an estimate."
Astronomers predicted the nova might appear in 2024. What's changed?
Astronomers with the Planetary Society last year predicted a 70% chance T-Cor would go nova by September 2024. Obviously, it didn't happen. What's changed, according to NASA, is that astronomers have observed T-Cor dimming suddenly, which is a sign it might go nova sometime in the coming months.
A video still from an animation provided by NASA, shows a white dwarf orbiting a red giant star. T Coronae Borealis a white dwarf could explode any time between now and the next several months and should be visible to the unaided eye for several days and just over a week with binoculars before it dims again.
How bright will the nova be?
The explosion caused by the nova will be so massive you'll be able to look up and see it in the night sky without a telescope, experts said, so it should be easy to spot. Hounsell said it will shine about as brightly as the North Star.
"It's going to be very, very obvious," Hounsell told IndyStar last year. "The star is only 3,000 light years away in the northern crown constellation, so it's going to be similar to Polaris, which is extremely bright."
That's roughly 17 quadrillion miles away. Even so, scientists with the Planetary Society said previously the nova explosion will likely be the brightest one witnessed on Earth since 1975.
Rendering of a binary star system: The 'Blaze Star', T Coronae Borealis (T CrB), will likely go nova in 2024.
What is a nova?
The word "nova" comes from the Latin word meaning "new." In astronomical terms, it can seem like there's a new star in the heavens even though that star might be very old and at the end stages of its life. During a nova event, explains NASA, energy explodes from a white dwarf star.
Hounsell said white dwarf stars aren't much larger in size than planet Earth. Usually they're too dim to see at night, but when a nova happens, the sudden explosion can make the star shine brightly enough to be viewed with the naked eye from trillions of miles away.
What causes a star to go nova?
Stars don't always play nice with each other, say experts. Most stars are bound by gravity to one or more companion stars, and things can get interesting — or violent — if these stars get too close.
Sometimes when a small white dwarf star orbits a regular star, it can siphon off the larger star's energy. That's because a white dwarf star has about the same mass as Earth's sun, Hounsell said. Its gravity is extremely powerful — not as strong as a black hole, according to the Adler Planetarium, but roughly 100,000 to 300,000 times the gravity on Earth.
"So material is being pulled away from the companion star by the gravity of the white dwarf," Hounsell said. "This material builds up in layers onto the white dwarf's surface and the layers get really, really hot, but the material can't expand."
Eventually, the pressure and heat trigger a massive thermonuclear explosion, Hounsell said, which is called a nova.
Story continues after photo gallery.
What's the difference between a nova and a supernova?
A supernova is the final, fiery explosion that can destroy a dying star. It can briefly outshine entire galaxies, writes Space.com, and radiate more energy than our sun will produce in its entire lifetime. But while supernovas occur only once, a nova can happen again and again.
After a nova explosion, the dwarf star remains intact and the cycle triggering another explosion starts over, which NASA says can take tens, hundreds or even thousands of years.
In T Coronae Borealis' case, the cycle repeats roughly once every 80 years, which is why most people will likely see it only once in their lifetime.
When did T Coronae Borealis last go nova?
The Reno Evening Gazette noted the most recent appearance of T Coronae Borealis in February 1946.
The last nova from T Coronae Borealis happened in February 1946. It also erupted 80 years before that in 1866. One astronomer described the event, saying, "In colour, the star appeared nearly white with a bluish tinge," according to documents preserved by IOPscience.
The first recorded sighting of the "Blaze star" was more than 800 years ago, according to NASA. An abbot named Burchard in Ursberg, Germany, noted in 1217 that he saw, "a faint star that for a time shone with great light."
Where you can look to see T Coronae Borealis nova explosion
T Coronae Borealis can be found in the Northern Crown constellation, writes EarthSky, which you can find easily enough by searching for the two brightest stars in the Northern Hemisphere.
Look for the Big Dipper and follow its handle pointing toward the star Arcturus. Next, find Vega, which is part of the Summer Triangle. By drawing a straight line from Arcturus and Vega, you'll find the constellation Hercules and the Corona Borealis, a horseshoe-shaped curve of stars.
Just a little bit below the Corona Borealis, experts say, is where the Blaze Star should appear.
The Blaze Star nova will be approximately where the little blue X appears on this star map, provided by NASA.
Need help finding stars, planets and constellations? Try these free astronomy apps
The following free astronomy apps can help you locate stars, planets, and constellations.
How long will the nova last?
The nova should last roughly a week, Hounsell said, reaching peak brightness in its first few days before fading away.
How often do stars go nova?
There are only five known stars in the entire galaxy that have nova events, writes NASA, but scientists believe the Milky Way experiences roughly between 30-60 nova explosions per year. These faraway stars are so distant they can't be seen with the naked eye because the light is obscured by gas and dust.
What happens if T Coronae Borealis doesn't go nova this year, or at all?
Then that would be interesting, said Hounsell.
"We know roughly from historical records it's supposed to be around every 80 years or so, but this is unpredictable science," she said. "If the nova doesn't go off in the timeframe we expect it to, then that might mean something different happened, leading us to figure out more information, which is really cool. We'll learn new things. That's the point of science."
How to say 'Uranus': Not to be cheeky, but you've been saying this gassy planet's name wrong your entire life.
John Tufts covers trending news for IndyStar and Midwest Connect. Send him a news tip at [e-mail]. Follow him on Twitter at JTuftsReports.
This article originally appeared on Indianapolis Star: T Coronae Borealis dims, shows sign it could go nova soon, says NASA