A sharp-eyed star gazer in Wyoming might catch a new star in the night sky this spring or summer. Beginning at any time now through the end of September, astronomers are expecting we can see the aftermath of a spectacular celestial event that happened 3,000 years ago.
Astronomers are awaiting a nova from T Coronae Borealis in the Northern Crown constellation, which is located between the constellations of the Boötes and Hercules. A nova is a brief moment when a flash of light from a binary star system shines brightly in the night sky.
The new light is so bright that T Coroane Borealis, ordinarily not visible to the naked eye, can potentially be spotted by Wyomingites. It won’t look like much, but it’s unusual to experience it from our small spot in the universe.
“Novas are a little subtle compared to supernovas,” said Max Gilbraith, the planetarium coordinator for the University of Wyoming Physics and Astronomy Department. “They are called new stars because they will briefly appear as a new light in the sky for a couple of months.”
Giants, Dwarfs, And Thermonuclear Energy
Novas might be called new stars, but that’s not what Wyomingites will see when it happens sometime in the next few months. Gilbraith said the bright light of a nova is a “momentary flare” from the outside of a dying star interacting with what’s left of the inside of a dead star.
First, some space science.
When sun-like stars run out of hydrogen in their cores, they grow to immense sizes, more than 200 times larger than our sun. Those stars are called red giants.
If a red giant isn’t large enough to become a neutron star or a black hole, it condenses into a white dwarf, roughly the size of our planet but as dense as the sun. Astronomers believe this happens to 97% of stars in the universe.
“A nova occurs when you've got a white dwarf, which is a dead sunlike star,” Galbraith said. “That’s got a companion sister star in its orbit. In this case, it's a red giant. And as the very hot inner core of the red giant expands, it causes the outer layers of that star to expand far enough away that they might deposit onto the surface of the white dwarf, the dead core of a sun.”
When this happens, the outer layer of the red giant causes rapid thermonuclear hydrogen fusion on the surface of the white dwarf. That energy creates the bright light that stretches through space.
“It’s a deposition from a dying star onto the core of a dead star that results in a momentary flare of bright light," Gilbraith said. “We're witnessing many millions and millions of instances of thermonuclear hydrogen fusion occurring.”
The light generated by the thermonuclear hydrogen fusion of the dead and dying stars will be the “new star” visible from Wyoming.
Bear in mind that these events happened more than 3,000 years ago. Around the same time the light from this nova was generated, King Solomon of Israel built the first temple in Jerusalem and the city of Rome wouldn’t exist for another 200 years.
Starry Subtlety
The light of the distant nova will reach Earth sometime in the next seven months. Astronomers won’t know for sure until it gets here.
When it does, Gilbraith is confident that anyone who wants to see the nova should be able to. Of course, they’ll need to find it first, which could be tricky.
“It's 3,000 light years from Earth, and that’s a very, very distant star that's further than we typically see with the naked eye,” he said. “Most of the stars in the constellations are within about 1,500 light years.”
Gilbraith said the nova will have a similar brightness to Polaris, the North Star. People might believe that the North Star is the brightest in the sky, but it doesn’t hold a candle to the truth.
“A lot of people, especially in urban environments, might struggle to see Polaris on a moonlit night,” he said.
It’s at the very edge of being visible to the naked eye, and it's not a particularly bright star.”
Astronomers don’t know when we’ll see the nova, but they know where. It’ll be visible in the constellation Corona Borealis, shining like a jewel in the Northern Crown. It’s a U-shaped constellation behind Hercules' back and under Boötes the Herdman’s elbow.
If that’s confusing, no worries. NASA has a guide to assist anyone straining to see the nova or anything else in the night skies.
Because there are so many visible stars in the night sky, Wyomingites might have a more challenging time than many others across the United States. Gilbraith recommends finding a spot with a dark sky and a telescope or binoculars for anyone serious about not missing the nova.
Bright Light, Big Boom
When a white dwarf vibes with energy thrown its way from a nearby neighbor, it manifests as a nova. When a white dwarf gets triggered enough, it manifests as a supernova.
Supernovas are the massive, explosive deaths of white dwarfs as they collapse into a new star or a black hole. They’re so bright they can outshine galaxies in the night sky.
They’re also much rarer. Astronomers can spot around 10 novae every year, but the last supernova visible from Earth was in 1604.
“In the past, supernovas could be brighter than planets in the nighttime sky, and then they fade relatively quickly over time,” said Gilbraith. “Those are the very violent deaths of very massive stars.”
Betelgeuse, a red giant on the shoulder of the constellation Orion, is the next star astronomers expect to explode into a supernova. When it goes, it could be as bright as the moon from our perspective on Earth and could even be visible during the day.
Want to mark your calendar? Don’t. The supernova of Betelgeuse could happen anytime in the next 100,000 years.
Last Candlelight
While not as spectacularly dramatic as a supernova, Gilbraith hopes Wyomingites will be curious enough to seek out Corona Borealis and observe the impending nova. Once its light gets here, it should be visible for several weeks, at least.
A nova, the latest visit from the devil comet, and a total solar eclipse in the Midwest in April. It’s already an eventful spring in space.
The nova might not be the brightest or most exciting sight in the night sky, but it’s quite important for science. Gilbraith said novae help astronomers measure precise distances in space, revealing our distance from other galaxies with much greater accuracy.
But T Coroane Borealis is special. It's one of only five recurring novae in the night sky, which means it has repeatedly sent flashes of light, usually once every 80 years.
A nova isn’t a new star, but it presents new opportunities for stargazers. Gilbraith described it as a candle from a long-dead star, lighting a way in the infinite darkness.
“A nova is a standard candle that always occurs at a characteristic mass,” he said. “It’s holding onto some mass thrown it from its neighbor, and it will briefly reignite that candle just a little.”
Andrew Rossi can be reached at arossi@cowboystatedaily.com.
