Solar eclipse fans still riding their high from totality have something else to look forward to this year, which could also be a once-in-a-lifetime celestial event to witness. A dance between two stars 3,000 light years away will culminate in a massive explosion so bright it will create the appearance of a “new” star in the night sky seen by the naked eye for several days and with a telescope for weeks. Astronomers expect this Nova explosion within the binary star system known as T Coronae Borealis, or T CrB, to happen between now and September. The last time this explosion was observed was in 1946.
Astronomer Gerard Van Belle, with the Lowell Observatory in Arizona, said the science community is eager for this explosion to happen so they can use modern telescopes to study it. Van Belle said, “You have one star that’s getting old and again, kind of expanding and sloughing off its outer material, and that’s falling on the cinder of an even older star that all this left behind is this, this ember of fire, really this thermonuclear core. As material gets piled on top of it from its companion, it finally explodes.”
One white dwarf star about the size of Earth and about as massive as the Sun is orbiting a red giant star, blowing off mass. Hydrogen falling onto the white dwarf accumulates over time, in this case, over about 80 years. Like meteor showers we see every year, people on Earth have been noting changes in the night sky for a very long time. With T CrB, this bright outburst was observed in the sky at least twice, 80 years apart, helping scientists determine it was a periodic event. Van Belle said, “We’re starting to get very long timelines in astronomy for some of these things. And so for this particular object, it was noticed in 1866 to brighten up. And then, 80 years later, in 1946, it brightened up again. It went from something that you can barely see with a pair of binoculars to something that you could walk outside and see with your own two eyes.”
Van Belle said that in the two previous explosions, the star brightened and dimmed over a two-year period, which has been happening again. “It looks like it’s ready to pop off,” Van Belle said. Unlike the solar eclipse or a meteor shower, astronomers can’t give us an exact time and date for the Nova explosion, but that could change over the next 80 years when the subsequent blast happens. Van Belle estimates that a future space telescope might make that possible. “Can we get to a point where we can be able to say, you know, ‘It’ll be 5 o’clock on Thursday,’? But we’re not there yet,” Van Belle said.
Based on the brightening and dimming observed over the past two years, the best estimate is that the explosion will happen between now and September.