T Coronae Borealis (T CrB) is a rare type of star known as a recurrent nova, which means it periodically explodes. This phenomenon occurs when material from its companion red giant star falls onto the smaller white dwarf star, causing it to build up pressure and eventually ignite, resulting in an explosion.
The last time T CrB was visible to the naked eye was in 1946, but scientists predict that it will erupt again soon. When this happens, the star will brighten to a magnitude of 2nd, making it visible from Earth, comparable to the brightness of the North Star (Polaris). However, this phenomenon is short-lived, lasting less than a day.
A recent observation by astronomers using the Alfred Jensch Telescope in Germany detected an increase in spectral lines indicating that T CrB’s white dwarf star is accreting matter at a higher rate, suggesting an impending explosion. While there has been no brightening yet, scientists are on high alert.
To spot T CrB, look for it just south of the line between Arcturus and Vega, or roughly 5½° east of Alphecca, one of the brightest stars in the Corona Borealis constellation. Keep an eye on Astronomy.com for updates, and if you’re lucky, you might witness this rare celestial event.
Source: https://www.astronomy.com/observing/when-is-t-crb-going-to-explode