Mark Your Calendars: T Coronae Borealis’ Once-in-a-Lifetime Nova in 2024

This year, you might be in for a once-in-a-lifetime celestial event! T Coronae Borealis, a special star system nicknamed the “Blaze Star”, is predicted to undergo a spectacular nova explosion¹ in 2024. 

Located in the constellation Corona Borealis (the “Northern Crown”), this recurring nova could soon become visible to the naked eye, putting on a dazzling show in the night sky.

What Is T Coronae Borealis?

T Coronae Borealis (T CrB for short) is a binary star system, meaning it consists of two stars orbiting each other:

• A red giant: a dying star that has puffed up to an enormous size
• A white dwarf: a small, dense stellar remnant with powerful gravity

Normally, T CrB shines at a feeble 10th magnitude, making it too faint to see without a telescope. But roughly every 80 years, the Blaze Star lives up to its name, suddenly flaring to 2nd magnitude – almost as bright as the North Star! This tremendous brightening happens when the white dwarf explodes in a nova outburst.

T CrB is one of only about 10 known recurring novae in the Milky Way galaxy. These rare systems provide valuable opportunities for astronomers to study the mass transfer and explosive processes in close binary stars. 

T CrB’s Nova History

T Coronae Borealis has a long and storied history of observed nova outbursts:

• 1217 & 1787: Possible ancient sightings found in historical records
• 1866: First confirmed eruption spotted by astronomer John Birmingham
• 1946: Most recent nova seen by amateur astronomer Leslie Peltier

Whenever T CrB erupts, it puts on a spectacular show. In 1866, it peaked at magnitude 2.0, almost rivaling the brightest stars in the sky. 

The 1946 blast reached magnitude 3.0. Peltier even noticed the star fading about a year before the outburst – an early warning sign that the next eruption was imminent.

The Next Big Blast: 2024

80 years after its last eruption in 1946, T Coronae Borealis is due to go nova again in the mid-2020s. Several lines of evidence point to 2024 as the most likely year for the next blast:

• Mathematical models of T CrB’s nova cycle predict an eruption around April-September 2024
• In early 2023, the star began dimming – the same pre-outburst fading seen in 1945
• If the 2024 eruption follows the same 11-month delay as in 1946, the nova should peak between February-October 2024

When the nova does happen, T CrB could brighten dramatically, potentially reaching 2nd magnitude. 

That would make it easily visible to the naked eye as a “new star” in Corona Borealis, outshining every other star in the constellation. Binoculars and small telescopes will enhance the view as the star slowly fades over a week or more.

How T CrB’s Nova Explosions Happen

The white dwarf in the T CrB system is a stellar vampire, slowly siphoning hydrogen gas from its bloated red giant companion. As this stolen material piles up on the white dwarf’s surface, it gets compressed and heated by the star’s powerful gravity.

After around 80 years of accumulation, the hydrogen reaches a critical temperature of 10 million Kelvin and ignites in a runaway thermonuclear explosion – essentially a gigantic hydrogen bomb! In a cosmic flash, the white dwarf expels the unburnt hydrogen in a rapidly expanding shell, causing its brightness to skyrocket 10,000 fold.

But the white dwarf itself survives the blast. The nova explosion only blows off the freshly accreted outer layers, leaving the underlying star intact. 

So after a few weeks, T CrB fades back to its normal brightness as the fireworks subside. Then the cycle begins anew, with the white dwarf slowly stealing more hydrogen from the red giant, building up to the next big boom decades down the line.

How to See the 2024 Nova

If you want to witness this once-in-a-lifetime nova for yourself, here are some tips:

1. Find the constellation Corona Borealis in the spring/summer evening sky. It looks like a semicircular arc or crown, located between the constellations Boötes and Hercules.
2. Center your gaze on the bright star Alphecca (Alpha Coronae Borealis) at the crown’s apex.
3. Look for a new, very bright star inside the arc of the crown that wasn’t there before. That will be T CrB in outburst!
4. Compare the nova’s brightness to nearby stars over several nights to watch it slowly fade.
5. Follow astronomy news outlets and social media to get alerts when the eruption begins.

The nova will be visible from most of the Northern Hemisphere, so you don’t need to travel to see it. Just find dark skies away from city lights, and enjoy the show!

Why Recurring Novae Matter

Beyond putting on a spectacular light show, recurring novae like T CrB have immense scientific value. They serve as cosmic laboratories for understanding the complex interactions and evolution of close binary star systems.

Each nova eruption is like a natural experiment, allowing astronomers to test theories of how mass and energy flow between the stars. Recurring novae reveal key insights about the fates of stars, from the death throes of red giants to the inner workings of white dwarfs.

Source:
1. https://www.forbes.com/sites/jamiecartereurope/2024/05/04/a-new-star-to-the-naked-eye-is-imminent-in-sky-event-53-times-rarer-than-a-total-solar-eclipse/