T Corona Borealis
T Coronae Borealis is also know as the Blaze Star, its a nova which erupted on May 12th 1866 eventually reaching magnitude 2.2 it then took only 8 days to fade below naked eye visibility. The star then stunned astronomers when on February 1946 T CrB went novae again reaching magnitude 3.0. It is what astronomers call a recurrent nova. There was a small number of other stars that had been observed to go novae more than once but they had not reached naked eye visibility.
Novae are binary systems with a small hot star and a large cooler star. The hotter star pulls some of the cooler gas from its companion, this gas then falls onto the surface of the hot star which then throws of a small shell of gas into space. We see this light and in the medieval period these were referred to as Nova. The word nova is Latin for new. Today we know that novae are not new stars.
T Corona Borealis is still called the ‘Blaze Star’ although over the pas 25 years astronomers have discovered that all nova are recurrent novae just as T Corona Borealis is. There periods can be measured over decades or centuries.