T Coronae Borealis

T Coronae Borealis (T CrB), nicknamed the “Blaze Star,” is a rare recurrent nova located approximately 3,000 light-years away in the constellation Corona Borealis (also known as the Northern Crown). It is a binary star system consisting of a red giant (with a radius of 63.5 and luminosity of 583) and a white dwarf (with a mass of 1.37 and luminosity of ~100), which interact to produce periodic nova outbursts. T Coronae Borealis experiences outbursts approximately every 80 years. Documented eruptions occurred in 1866, 1946, and the next is anticipated soon, though predictions have varied between 2024 and 2025 based on recent observations.
 
The red giant companion star continuously sheds matter, which is pulled onto the white dwarf by its intense gravity. This matter forms an accretion disk around the white dwarf before settling on its surface. Over decades, a layer of hydrogen-rich material builds up on the white dwarf’s surface. As this layer grows, the pressure and temperature at its base increase. When the temperature and pressure reach critical levels, hydrogen fusion ignites in a runaway thermonuclear reaction. This explosion releases an enormous amount of energy, causing the system to brighten dramatically. The sudden release of energy ejects material from the white dwarf’s surface, producing the nova event. The brightness can increase by several magnitudes, making T CrB visible to the naked eye. After the outburst, the system returns to a quiescent state, and the process begins again, leading to periodic eruptions approximately every 80 years.
 
Astronomers have been closely monitoring T CrB since it entered a pre-eruption dimming phase in March 2023, similar to behavior observed before its previous explosions. Predictions initially suggested an eruption in 2024, but deviations have delayed the event. The outburst of T Coronae Borealis is expected to last for several days as a naked-eye visible event, followed by approximately a week of visibility with binoculars before dimming back to its usual magnitude. However, the peak brightness — around magnitude +2 (comparable to Polaris (the North Star) — may last less than a day.
 
T CrB is one of only a few recurrent novae known, making it an important subject for studying binary star interactions and nova mechanisms. Its unpredictable behavior continues to intrigue astronomers worldwide.
 
References:
Ashley. (2025, January 4). T Coronae Borealis Nova. Judicial Data. https://judicial.mc.edu/t-coronae-borealis-nova
 
Bakich, M. E. (2025, March 4). When is T Coronae Borealis Going to Explode?Astronomy. https://www.astronomy.com/observing/when-is-t-crb-going-to-explode/
 
Corona Borealis. (2025, March 1). In Wikipedia. https://en.wikipedia.org/wiki/Corona_Borealis

​Pearson, E. (2025, February 18). T Coronae Borealis nova set to become a 'new star' in the sky, and will be as bright as the North Star. BBC Sky at Night Magazine. https://www.skyatnightmagazine.com/space-science/t-coronae-borealis-nova
 
T Coronae Borealis. (2025, March 8). In Wikipedia. https://en.wikipedia.org/wiki/T_Coronae_Borealis
 
Wiessinger, S., Gutierrez, A.M. (2024, November 4). T Corronae Borealis Nova Animations. NASA Scientific Visualisation Studio. https://svs.gsfc.nasa.gov/20393