A possibly once-in-a-lifetime “Blaze Star” will be visible to the naked eye in D-FW night skies sometime between now and September.
Despite its name, the Blaze Star actually consists of two companion stars — a white dwarf and a red giant — in the constellation Corona Borealis, some 3,000 light years away. This star duo is known to scientists as a binary system and is called T Coronae Borealis.
About every 80 years, T Coronae Borealis grows up to 1,700 times brighter, becoming about as bright as the North Star, Polaris, said Phillip Anderson, director of the William B. Hanson Center for Space Sciences at the University of Texas at Dallas. This event is called a recurrent nova, of which about 10 are known in the Milky Way galaxy.
As a star like the Sun ages over billions of years and burns up its hydrogen for fuel, it eventually becomes a very hot, dense remnant called a white dwarf. With its immense gravitational force, the white dwarf in T Coronae Borealis is siphoning off hydrogen from its nearby red giant, a large, relatively cool star also nearing the end of its life.
“The white dwarf is building up a layer of hydrogen; it’s heating up more and more,” Anderson said. “Eventually, it reaches a point where hydrogen fusion begins as an explosion.”
The celestial blast releases a brilliant flash of light that becomes visible to us as a twinkling star. This cycle continues many times during the star system’s lifespan, which makes it different from a supernova, a massive explosion that results in a star’s death.
The first eyewitness record of the Blaze Star was in 1217 by a German monk who described it as “a faint star that for a time shone with great light,” according to NASA. Other occurrences observed from Earth were in 1787 and 1866, with the latest in 1946.
By comparing the star system’s current brightness to what was observed in 1946 and 1866, Anderson said, scientists anticipate T Coronae Borealis will glow brightly sometime in the next two months.
North Texans will be able to see T Coronae Borealis at night by locating the Corona Borealis, which lies between the constellations Hercules and Boötes. Anderson recommends using a stargazing app such as Star Walk for guidance.
“What I would suggest is going out at night every once in a while and get used to finding Boötes, Hercules, Corona Borealis and Alphecca,” he said. “Find where you expect to see the star and then one day, you’ll go, ‘Oh look, there’s a star I haven’t seen before.’”
You can otherwise try scoping out the sky about 15 degrees above the horizon just after sunset.
Once T Coronae Borealis explodes, the brightening will be brief, about less than a week. But it will provide scientists a perfect opportunity to better understand recurrent novas, Anderson said.
“We’re watching stellar evolution. … Being able to watch this in real time, in our lifetime, is amazing.”
Miriam Fauzia is a science reporting fellow at The Dallas Morning News. Her fellowship is supported by the University of Texas at Dallas. The News makes all editorial decisions.