A star will soon get much, much brighter. And then it will fade again for another 80 or so years.
In 1980, American astronomer Carl Sagan famously said, “We are made of star stuff.”
Today, the saying can mostly be found on inspirational social media posts. It’s become a colloquial term for something that sounds sweet, but surely can’t be true.
Or is it?
Sumner Starrfield is a computational astrophysicist and regents professor of Astrophysics at Arizona State University. He landed at ASU in 1972 and has worked on stellar explosions for over 30 years.
“I tell my students that all of the chemical elements that make up the solar system; your bodies, the rocks you walk on, come from stars at one point or another,” Starrfield said. “The only elements produced in the initial formation of the universe were hydrogen and helium and a couple of trace things.”
Nuclear fusion occurring in previous generations of stars is the reason that carbon, nitrogen and oxygen atoms exist in our bodies. Heavier elements, like iron, and basically everything else that exists in the natural world, apart from hydrogen and helium, were made in the hellish furnace of stars billions of years ago.
One particular upcoming stellar explosion, called T Coronae Borealis, will be studied extensively by Starrfield and his team of 11, composed of scientists from India, England and the United States. T Coronae Borealis, also known as the Blaze Star, is what’s called a recurrent nova. It explodes roughly every 80 years. The last time it exploded was in 1946, but the first recorded time could have been as early as 1217 A.D. Scientists estimate that only about 10 recurrent nova exist in our galaxy.
Supernovae and novas sound similar, but they’re actually two completely different things. In the case of T Coronae Borealis, a pair of stars, a dense white dwarf roughly the size of Earth but with the same mass as our sun and an ancient red giant exist together in a binary companion system. Over time, the white dwarf accretes hydrogen from the red giant, making it bigger and hotter. The nova occurs once the white dwarf has absorbed too much hydrogen from the red giant, fusion occurs, and a thermonuclear explosion blasts away all the accreted material back into space. Then the cycle begins again. Novas allow for the dwarf star to stay intact, but supernovas destroy their host star.
“A supernova is an event that essentially is way more energy and way brighter than a nova, but also it’s kind of the end of a certain type of (high mass) star’s life.” Adam Fritsch said, an associate professor of physics at Gonzaga. “The only thing that’s really similar about them is they do happen in stars and they do become very, very bright.”
When T Coronae Borealis explodes, it should be visible from Earth. In fact, it will probably be one of the brightest objects in the sky as it’s supposed to be 1,500 times brighter than it normally is. NASA believes it should shine about as brightly as the North Star, Polaris. Observers looking for this once-in-a-lifetime cosmic event should look in the Northern Crown, a horseshoe-shaped assortment of stars west of the constellation Hercules. Downloading an interactive star chart, like Stellarium, may be a more effective way to spot exactly where T Coronae Borealis is in our sky.
T Coronae Borealis could explode at any point. Fritsch said that scientists are able to tell when the recurrent nova will explode based upon previous observations of when it dims and brightens. Many believe the nova will explode in September, but Starrfield is not so sure.
“I have no idea who came up with the September guess. But my feeling is that we’re looking somewhere in the middle of 2025, maybe even to the beginning of 2026.” Starrfield said.
Once the nova explodes, whether that’s in a week or a year, Starrfield and his team will create a computer model of the nova and then write research papers on what they’ve discovered. Their findings will be published in some of the top journals, like the Astrophysical Journal. Part of their research is funded by NASA, Starrfield said.
Christian Iliadis is a J. Ross MacDonald Distinguished Professor of physics and astronomy at the University of North Carolina. He will lend his expertise on experimental nuclear astrophysics for the project.
“In his (Starrfield’s) computer models, what he needs are these so-called nuclear reaction rates,” Iliadis said. “So I provide all the nuclear physics, the nuclear reaction rates, the probabilities that certain reactions will proceed.”
Starrfield’s main concern is that the nova could potentially explode when it’s hidden behind the sun. If that happens, they won’t be able to observe T Coronae Borealis until it moves from behind the sun.
Iliadis believes that the nova explosion will not only serve as an inspiration for future generations of astronomers, but it should also provide a unique opportunity to learn all kinds of new things about novas.
“We want to know what the internal composition of the star is,” Starrfield said. “We want to get an idea of how much material is ejected and how fast. … We’d like to know how bright it is, and we would like to know if we can measure some of the elements that it ejects.”
Starrfield said he’s not only excited for what can be discovered from this specific event, but from all the new discoveries and things to study available for future generations of astronomers. Even 40 years after Sagan first said it on a 13-part series called “Cosmos,” it appears science has only backed up the notion that we really, truly are made of star stuff.
“We are a way for the universe to know itself,” Sagan said. “Some part of our being knows this is where we came from. We long to return. And we can, because the cosmos is also within us. We’re made of star stuff.”