How to watch a “once in a lifetime” nova explosion in the sky over the USA

The night sky may be getting a brand new star in the next few weeks.

T Coronae Borealis, also known as the Blaze Star or T CrB, is a binary star system located about 3,000 light-years from Earth and could explode in a spectacular fashion any day now.

Normally T CrB is too dim to be seen with the naked eye, but during its explosion (nova) it is expected to temporarily shine brighter than Polaris.

T CrB is one of only five known recurring novas in our galaxy. It consists of a white dwarf and a red giant orbiting each other in a binary star system, with the white dwarf undergoing a strange regular nova explosion about every 80 years – the last one was observed in 1946. Researchers have found that the star’s recent behavior is strikingly similar to the period before its last outburst, suggesting that another outburst is imminent before September of this year.

How to recognize T-CrB

To find T CrB, skywatchers should look to the Northern Hemisphere’s summer sky. T CrB is located in the constellation of Kronos, a distinctive horseshoe-shaped pattern of stars between the constellations Hercules and Ursa Major. To find it, draw a straight line between the Northern Hemisphere’s two brightest stars – Arcturus and Vega – and then look between them to find the arc-shaped Kronos. You can accurately find the reddish-hued Arcturus by following the handle of the Big Dipper constellation.

Once the explosion occurs, it will be visible for less than a week. To best see the nova, observers should look into the night sky shortly after sunset. The exact timing is unpredictable, but astronomers are confident the event will occur by September 2024. Hopeful stargazers will be able to see the star best far away from light pollution.

Normally, T CrB has a magnitude of +10, making it invisible to the naked eye. Magnitudes are measured backwards in astronomy, with a lower number or a higher negative number meaning an object is brighter—the full moon has a magnitude of -13, while the stars Sirius and Arcturus have magnitudes of -1.5 and -0.05, respectively. If an object has a magnitude of +6 or less, it is visible to the naked eye. T CrB is expected to reach a magnitude of around +2 at its brightest, making it about as bright as Polaris, the 48th brightest star in our sky.

“It’s a once-in-a-lifetime event that will create many new astronomers. It offers young people a cosmic event that they can observe for themselves, ask their own questions and collect their own data,” said Rebekah Hounsell, a research assistant specializing in nova events at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in a NASA statement. “It will power the next generation of scientists.”

Due to a strange property of the white dwarf-red giant binary star system, T CrB goes nova about every 80 years. The white dwarf, the remaining core of a collapsed star, slowly sucks up the hydrogen gases from the red giant’s atmosphere, growing larger and hotter, until it finally explodes in a thermonuclear explosion, known as a nova. These novae are less powerful than supernovae, which destroy a star completely at the end of its life.

After this explosion, the process starts all over again. That’s why T CrB explodes about every 80 years. The star system is behaving very similarly to how it did just before the last explosion, so astronomers are fairly certain that a nova will occur before September of this year.

“There are some recurrent novae with very short cycles, but we don’t usually see a repeated outburst very often in a human lifetime, and rarely one that occurs so relatively close to our own system,” Hounsell said. “It’s incredibly exciting to have a front row seat to it.”

Astronomers hope to study the upcoming nova in detail using several telescopes around the world, including NASA’s Fermi Gamma-ray Space Telescope and James Webb Space Telescope.

“Typically, nova events are so faint and distant that it’s hard to clearly identify where the energy of the flares is concentrated,” Elizabeth Hays, director of the Astroparticle Physics Laboratory at NASA Goddard, said in the statement. “This event will be very close, many eyes will be on it, studying the different wavelengths and hopefully giving us data that we can use to begin to decipher the structure and specific processes. We can’t wait to get a complete picture of what’s going on.”

However, there is a small possibility that the nova will not occur at all before September.

“Recurrent novae are unpredictable and inconsistent,” Koji Mukai, an astrophysicist at NASA Goddard, said in the statement. “If you think there can’t possibly be a reason for them to follow a particular pattern, they do – and as soon as you rely on them to repeat the same pattern, they deviate completely from it. We’ll see how T CrB behaves.”

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