Blaze Star — Variable Star in Corona Borealis

T Coronae Borealis, nicknamed the Blaze Star, is one of only ten known recurrent novae in our galaxy and by far the most famous. The system is a close binary about 2,700 light-years away in Corona Borealis, consisting of a hot white dwarf accreting hydrogen-rich material from a red giant companion in a 227.6-day orbit. Roughly every 80 years, enough material accumulates on the white dwarf's surface to trigger a runaway thermonuclear flash — a nova explosion that briefly raises the system's brightness from a quiescent magnitude 10 up to about magnitude 2, comparable to Alphecca or Polaris. Recorded outbursts occurred in 1866 and 1946, and astronomers have predicted that the next eruption is imminent — anticipated within the current observing season.

In quiescence T CrB sits at magnitude 10 and requires a small telescope to spot, located in the small triangle of stars just east of the curve of Corona Borealis, between Epsilon CrB and Iota CrB. The real target, however, is the next outburst: when it erupts, the star will appear within hours as a brand-new naked-eye 'star' in the Northern Crown, briefly turning the constellation's familiar arc into something unfamiliar. Memorise the empty patch where T CrB belongs so you can recognise the change instantly. After peak (magnitude ~2), the nova will fade rapidly — about a magnitude per day — vanishing back to telescopic territory within a week or two. Any binoculars or small scope will be enough to follow the decline. Best observed from April through September when Corona Borealis is high in the evening sky.

First seen in outburst by John Birmingham of Tuam, Ireland on 12 May 1866, when it briefly reached magnitude 2.0 and was named T Coronae Borealis under the standard variable-star nomenclature. The 1866 outburst was a major scientific event — William Huggins recorded one of the earliest stellar spectra of a nova during the eruption. The star then faded back to obscurity until 9 February 1946, when Armin Deutsch and others recorded a second outburst peaking at magnitude 3.0 — confirming the recurrent nature of the explosion and establishing T CrB as the prototype recurrent nova. Since the late 2010s, photometric and spectroscopic precursor signatures (a 'super-active' state followed by a deep pre-eruption dip, mirroring the 1946 sequence) have led astronomers to predict the next outburst sometime around 2024-2026.