Paper Suggests Longer Wait For Nova Eruption. Oh, Well.
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"Ruh-roh", as George Jetson's dog Astro would say. The observing campaign to witness a recurring nova erupt after an 80-year hiatus may be longer than anticipated. The new analysis of known previous events suggests accreted mass around the star T Coronae Borealis (T CrB) is likely to blow up closer to the first half of 2027, centered around March 25.
In early 2024, astronomers observed a "pre-eruption dip" in the brightness of the star T Coronae Borealis, a precursor of the faint star rapidly brightening as a nova in 1946. They reasoned the 2024 dip indicated an eruption was again imminent, and advised observers to be on the lookout. "To the ramparts!" But as of this writing, nothing happened.
Alan Binder, Director of the Lunar Research Institute, writes the periods between the previous events--1787, 1866, and 1946--are decidedly shorter than the oft-suggested 80-year period. Yet the period between the past successive eruptions appears to increase with time. Binder presents 7 models and assesses the viability of each before making his conclusion, provided the recurring nova "behaves in a regular, predictable manner." If not, all bets on timing are off.
Binder's analysis, Empirical Studies of the Timing of Nova Events of the Recurring Nova, T Coronae Borealis, appeared May 18, 2026, on the AAVSO website's Observing Campaigns #875: Monitoring T CrB. If the period were not increasing between events, "A more reasonable deduction from this exercise may be had by simply adding the derived, constant period of 81.046 years between events to the actual date of the last event, i.e., the 1946.110 event. This gives the date of 2027.156 or Feb. 26, 2027, for the next event, a date that seems reasonable, given the small amount of data at hand."
A different paper by Jean Schneider suggests because "previous T CrB eruption dates were separated by an integer multiple of the orbital period 228 days, the next eruptions should appear at 2025 March 27, 2025 November 10, 2026 June 25 or 2027 February 8." Schneider also notes, "No physical hypothesis is made behind this extrapolation." Specific dates are mathematical conclusions, not assertions of certainty.
Suggestions of a possibly extended observing campaign elicit a long groan from me, for I've been monomaniacal in imaging Corona Borealis nightly. June 14, 2026, marked the two-year anniversary of my going out every calendar day when it's clear enough to get an image of the Northern Crown with my cell phone camera. That would be over 460 nights so far.
But that's how science works. We observe and make predictions based on the data. So far, one conclusion from this delayed gratification of seeing a recurring nova with the naked eye is that--surprise!--a pre-eruption dip is not necessarily a prime indicator that an eruption is imminent. Lesson learned.
