In 2022, there will be a spectacular sky show. Two stars will merge into one, pushing out excess gas into an explosion known as a red nova. At magnitude 2, it will be as bright as Polaris in the sky, and just behind Sirius and Vega in brightness. The collision in the constellation of Cygnus will be visible for up to six months.
That’s pretty impressive. What’s more impressive: we’ve never been able to predict a nova before. But Lawrence Molnar, a professor of astronomy and physics at Calvin College, was able to find a pair of oddly behaving stars giving an indication of what might happen.
The objects, termed KIC 9832227, are currently contact binaries. Contact binary refers to two objects that are so close they are currently touching. The object was discovered by Kepler. The expected outcome is a merger between the two stars that will put on quite a show. Because both are low mass stars, the expected temperature is low, with Molnar terming it a “red nova.”
So how does Molnar know what will happen? After all, as he puts it, it’s “a very specific prediction that can be tested, and a big explosion.” He and his team have an example to look at: V1309 Scorpii. First observed in 2008, astronomers were able to watch the light curve as the event unfolded. First, there were a few “booms” in the sky. Then, a spectacular light show unfolded. Using precovery data, astronomers were able to trace back the evolution from 2001 on, giving a big picture of the decade of progression of the event.