Stars can sometimes create cataclysmically bright explosions, sudden unexpected changes that make some stars visible across the universe. And one of these stars might be ready to go off in our galactic backyard.
T Coronae Borealis (T CrB), which is 2,500 light-years away, is a variable star in the constellation of the Northern Crown. It’s known as a recurrent nova, a star that undergoes sudden bursts of luminosity by becoming more than 1,000 times brighter. Knowing this, it’s not difficult to understand why it’s nicknamed the Blaze Star.
Most of the time, the star has a magnitude of 10 – 10,000 times less bright than Saturn in the sky – and can only be observed with a good pair of binoculars. But twice in the last 130 years, the star has suddenly flared up.
On May 12, 1866, T CrB did just that, reaching a magnitude of 2 and making the star 1,580 times more luminous than usual and as bright in the sky as Polaris. A similar flare was observed on February 9, 1946, when the Blaze Star reached a magnitude of 3.
As reported by Sky & Telescope, over the last few months, the star has been increasing in luminosity and it is now four times brighter than typical. This slow increase in brightness is not the only reported change. T CrB is also getting bluer. The last time this happened was in 1938, and it is believed to be a precursor to a bigger flare.
T CrB is believed to be a binary system made of a red giant star and a white dwarf orbiting each other every 227 days. The hydrogen envelope that surrounded the red giant is now being taken in by the white dwarf. Every once in a while, this stolen gas gets too massive, ignites nuclear reactions, and produces a bright flash, thus creating the ephemeral nova explosion.
But the recurring nova is not the only thing that might happen to T CrB. If the white dwarf can steal enough hydrogen from its companion to reach 1.4 times the mass of the Sun, then it will turn into a supernova, and although we are at a safe distance, it will be tens of times brighter than the full Moon. So keep an eye on the Blaze Star, it’s definitely up to something.
[H/T: Sky & Telescope]
2
