T Coronae Borealis, a binary star system 3,000 light-years from Earth, is a ticking time bomb waiting to explode. And if the recurring nova follows its usual pattern, we can expect a new, albeit temporary, star to appear in our night sky every day.
The moderator of a citizen science group I recently joined emphasized: “T CrB remains our top priority target every night.” His urgency is understandable; Our Cosmic Cataclysms group must look for the expected nova and collect data before, during and after the explosion. It could appear at any moment, offering astronomers, whether amateur or professional, the opportunity to observe and study a rare and spectacular event in real time as it unfolds.
The data collected from this event is expected to improve our understanding of the dynamics of binary star systems and the complex life cycle of stars. Very cool. But what’s just as cool is that the nova is expected to be exceptionally bright. So bright that it is visible to the naked eye and appears as a new star in the sky, at least for a few days.
Once it is visible and you get the chance to see it, you can claim to have witnessed a runaway thermonuclear reaction from 3,000 light-years away. The plan is to add this to my recent naked eye successes – the most recent occurred during the total solar eclipse on April 8th. Like millions of others, I discovered ledges, appear as bright red dotsduring totality.
T Coronae Borealis (T CrB), also called Blaze Star, last exploded in 1946 at intervals of about 79 years. The current window opened last February and will continue into the spring and summer. T CrB, one of only five known recurring novas in the Milky Way, is a binary star system consisting of a heavy white dwarf and a red giant. They are only 0.54 astronomical units apart, about the distance from the Sun to Venus, and their close encounters have made T CrB a ticking time bomb.
White dwarfs are the final stages of medium-sized stars, but this particular white dwarf, about 1.37 times the mass of our Sun, races towards it The Chandrasekhar border– an astronomical limit at around 1.4 solar masses, beyond which white dwarfs become unstable.
The red giant, about 1.12 times the mass of our Sun, orbits the white dwarf every 227 days, bringing it to its center Roche flap, a boundary where his material begins to leak onto his nearby companion. This process forms an accretion disk around the white dwarf – a swirling vortex of stellar material.
When enough red giant hydrogen accumulates on the white dwarf’s surface, it heats up to extreme temperatures. This intense heat triggers a runaway thermonuclear reaction, turning the accumulated hydrogen into a cosmic fireworks display called a nova. In the case of T CrB, this explosive event repeats approximately every 79 years. Which is…looks at the clock…..pretty much right now.
With a magnitude of +10, T Coronae Borealis is currently invisible to the naked eye. However, the impending explosion will boost the star system to magnitude +2, a brightness similar to that of the Pole Star, also known as the North Star. The system, visible to observers in the Northern Hemisphere, is located in the constellation Corona Borealis. This constellation forms an arc shape, and once visible, T CrB will appear temporarily in this part of the night sky.
In the days and weeks following the expected burst, T CrB will gradually dim and return to its low brightness. It remains visible to the naked eye for several days after the explosion, and just over a week through telescopes and binoculars. After this time, the star system returns to its resting phase. Rinse, repeat, explode again, probably in 2103. As for the Nova, which is expected sometime this year, I will heed our moderator’s advice and make it my top priority target.
More: Astronomers are watching in real time as an epic supernova potentially creates a black hole