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Astronomers expect a “new star” to appear in the night sky any time between now and September, in a celestial event years in the making, according to NASA.
“This is a unique event that will create many new astronomers, giving young people a cosmic event that they can observe for themselves, ask their own questions and collect their own data,” Dr Rebekah said. Hounsell, an assistant research scientist specializing in nova events at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement. “This will fuel the next generation of scientists.”
The expected brightening event, known as a nova, will occur in the Milky Way’s boreal corona, or northern corona constellation, located between the constellations Boötes and Hercules.
While a supernova is the explosive death of a massive star, a nova refers to the brief, sudden explosion of a collapsed star known as a white dwarf. The dwarf star remains intact, releasing material in a repeating cycle that can occur over thousands of years.
“There are a few recurring novae with very short cycles, but in general we don’t often see a repeated explosion over the course of a human lifetime, and rarely this close to our own system,” Hounsell said. “It’s incredibly exciting to have this front row seat.”
T Coronae Borealis, also known as the “Blaze Star”, is a binary system in the Corona Borealis that includes a dead white dwarf star and an aging red giant star. Red giants form when stars have exhausted their reserves of hydrogen needed for nuclear fusion and begin to die. In about 5 or 6 billion years, our Sun will become a red giant, swelling and expanding as it sheds layers of material and likely evaporating the solar system’s inner planets, although the fate of Earth remains uncertain, according to NASA.
Every 80 years or so, T Coronae Borealis experiences an explosive event.
The stars in the orbiting pair are close enough to each other to interact violently. The red giant becomes increasingly unstable over time as it heats up, shedding its outer layers which land as matter on the white dwarf star.
The exchange of matter causes the white dwarf’s atmosphere to gradually warm until it undergoes a “runaway thermonuclear reaction,” resulting in a nova as shown in the animation below, according to the space agency .
A nova was being released from T Coronae Borealis in the fall of 1217 when a man named Burchard, Abbot of Ursberg, Germany, noted his observation of a “faint star which shone for a time with great light”, according to NASA. This was the first recorded sighting of the Blaze Star.
T Coronae Borealis experienced its last explosive explosion in 1946, and astronomers are once again monitoring the star system.
“Most novae occur unexpectedly, without warning,” William J. Cooke, head of NASA’s Weather Environments Office, said in an email. “However, T Coronae Borealis is one of 10 recurrent novae in the galaxy. We have known since the last flare in 1946 that the star will lose its brightness for a little over a year before rapidly increasing its brightness. T Coronae Borealis began to wane in March last year, so some researchers expect it to go nova by September. But the uncertainty about when this will happen lasts for several months – we can’t do better than that with what we currently know.
The star system, located 3,000 light years from Earth and generally too dim to see with the naked eye, is expected to reach a brightness level similar to that of Polaris, or North Star.
Once the nova’s brightness reaches its peak, it will be as if a new star has appeared – a star visible for a few days without any equipment and a little over a week with binoculars before dimming and disappearing of sight for about 80 years.
The nova will appear in a small arc between the constellations Boötes and Hercules and will be visible from the northern hemisphere.
NASA
The nova is expected to appear in the constellation Corona Borealis, also known as the Northern Corona.
“The northern corona is a horseshoe-shaped curve of stars west of the constellation Hercules, best spotted on clear nights,” according to a statement shared by NASA. “It can be identified by locating the two brightest stars in the northern hemisphere – Arcturus and Vega – and following a straight line from one to the other, which will lead skywatchers to Hercules and the Crown Borealis.”
The event promises to be exciting for amateur astronomers, said Dr. Elizabeth Hays, head of the Astroparticle Physics Laboratory at NASA Goddard.
“Citizen scientists and space enthusiasts are always looking for strong, bright signals that identify nova events and other phenomena,” Hays said. “Using social media and email, they will send instant alerts and the flag will be raised. We are again counting on this interaction of the global community with T CrB.
Astronomers will observe the nova using a range of telescopes on the ground and in space, and data from citizen scientists could also help astronomers piece together what happens before the eruption, Hounsell said.
Typically, nova events are so distant and faint that it’s difficult to identify the full picture of the flare, but “this one will be very close, with a lot of eyes on it,” he said. Hays said.
“Studying recurrent novae like T Coronae Borealis helps us understand mass transfer between stars in these systems and provides insight into the thermonuclear runaway that occurs on the white dwarf surface as the star passes into nova,” Cooke said.
Cooke recalled that the last nova he witnessed – Nova Cygni in 1975 – had a brightness similar to that expected from T Coronae Borealis. Nova Cygni should not experience another explosion again.
“I was a teenage astronomy enthusiast about to start college and I was out on the night of August 29,” Cooke said. “As I looked at the sky, I noticed that the constellation Cygnus was in disarray; there was a star that shouldn’t be there. After hearing a few comments from friends who thought I was crazy, I made them look and we realized that we were dealing with a nova! It was a very memorable experience and solidified my career choice in astronomy. I used to joke that a star had to explode to make me suffer while studying physics.
While it’s possible that T Coronae Borealis won’t explode by September, astronomers plan to monitor it just in case.
“Recurring novae are unpredictable and counter-current,” Dr. Koji Mukai, an astrophysics researcher at NASA Goddard, said in a statement. “When you think there can’t be any reason why they follow a certain established pattern, they do – and as soon as you start relying on them to repeat the same pattern, they deviate from it completely. We will see how T CrB behaves.