T Coronae Borealis: The star is about to explode and will be visible to the naked eye very soon | The science

Like people, stars are born, grow and die. And they do this in events that cause big explosions. A supernova is the death of a supergiant star, while a nova leaves stars alive after a sudden explosive outburst. Overall, these events are difficult to predict, but at least 10 white dwarf systems are known to periodically produce new stars, five of them in our galaxy. This is the case of T Coronae Borealis. (T CrB), located approximately 3000 light years from Earth. Its historical observations indicate that it explodes approximately every 80 years, and this cycle is close to completion. Once this happens, it will be visible to the naked eye as a nova in the night sky.

According to NASA, it is highly likely that the two-star T CrB system will again cause a huge explosion. The last time it happened was in 1946, and some astronomers have suggested it will happen again between February and September this year. However, other experts prefer not to risk giving such a rough estimate. Sumner Starrfield, an astronomer at the University of Arizona who has observed the nova’s behavior, explains the date of the long-awaited event: “It could happen tonight, this fall, or it could be in 2025 or 2026.

It is impossible to determine when it will actually explode. “Our estimates that this will happen soon are based on observations of its behavior just before the explosion 80 years ago.” Javier Armentia, an astrophysicist and director of the Planetarium of Pamplona, ​​agrees not to rush into a prediction: “The current behavior gives us clues, but it is impossible to give a definition.”

Every time a new star appears in the sky, it is called not going to –new, in Latin—; although in reality it is an astronomical event that causes an explosive flare of an already present star. T CrB actually consists of two stars: a red giant and a white dwarf. The second is the dense stellar core, the gravity of which attracts the gas of the red giant. The gas builds up on the dwarf’s surface until it explodes in what Armentia describes as an “extremely violent” event. The star temporarily glows more intensely and reaches the brightness of Polaris. Eventually everything returns to normal and the cycle repeats.

Seeing this new star is a once-in-a-lifetime opportunity. The size difference between the two stars is so great that it takes the white dwarf 227 days to orbit its red giant, Starrfield explains. They are so close that the material ejected by the red giant accumulates near the surface of the white dwarf. Once mass roughly the size of Earth accumulates in a white dwarf (which takes about 80 years), it warms up enough to start a runaway thermonuclear reaction. This causes a huge explosion, as “in a few seconds the temperature increases by 100 to 200 million degrees Celsius,” the astronomer details.

A stellar explosion can manifest itself quite noticeably in space. Depending on the magnitude and distance, the event can be observed with the naked eye or using homemade telescopes. The new T CrB will be visible to the naked eye. If what happened in its last explosion happens again, it will be visible for about a week, and after a couple of months the system will return to calm: “We will see it throughout its evolution,” Starrfield explains.

Novae are rare phenomena, so both astronomers believe this will be a great opportunity to expand knowledge about them. “We don’t know much about the new ones. “We have more advanced data and technology now than we did in 1946,” describes Armentia. And according to Starrfield, the big event will reveal how much energy is involved in the explosion, how much of that material is released into space, what the chemical composition of the gases is and how the Big Bang occurs.

“Gas coming out in a huge cloud? Or there are questions in many smaller clouds that Starrfield is looking for answers to. He is optimistic and assures that there will be more information “that will surprise us.” Through the observation of novae, Starrfield explains, signs have been found that some of the material that formed the solar system may have come from novae explosions. “We are pretty sure that lithium in the solar system comes from explosions of new stars that occurred before the formation of the solar system,” he explains. Regular novae explode “perhaps every 100,000 years,” he adds. But repeated new flares repeat their flares throughout human existence due to the peculiar relationship between the two stars.

This is at least the third time that humanity has witnessed a new T CrB, officially discovered by Irishman John Birmingham in 1866 and then reappeared in 1946. In anticipation of the next big bang, astronomers are invited to explore the constellation Corona Borealis, or the Northern Crown, which is a small semi-circular arc between Arthur’s star – one of the brightest and easiest to spot – and the constellation Hercules. “This is where the burst will appear as a bright new star,” NASA experts explain.

Starrfield’s team booked time with the space telescope James Webb watch for the eruption, but it will be just one of many eyes on the outbreak once it begins. Such advanced technology is not necessary to witness this extraordinary event when it occurs. The star will be visible to the naked eye for about a week; and with binoculars, for a month. You just need to go out and look at the constellation Corona Borealis.

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