In autumn, a new star will appear in the sky. A nova is exploding in the Corona Borealis system, which lies about three thousand light-years from Earth. The white dwarf T Coronae Borealis does this regularly in the cycle of approximately one human lifetime, i.e. eighty years.
The American space agency NASA has announced that this event should most likely occur by September 2024. And when it happens, the bright light of the nova will apparently be visible with the naked eye.
The last time this white dwarf, the otherwise inactive core of a collapsed star, brightened was in 1946.
“I’m absolutely thrilled. This thing is kind of like Halley’s Comet. It appears once every 75 to 80 years, but novae are not talked about nearly as much as comets,” NASA astronomer William Cooke described his joy.
Star weather forecast
The star system, which is too faint to be visible to the naked eye, will enlarge during the event to a brightness similar to that of the North Star. Once brightness reaches its peak, the nova should be visible to the naked eye for several days and a little over a week through binoculars. Then it will go dark again, possibly for another eighty years, NASA predicts.
This event is usually impossible to predict because novae explode unexpectedly. But there are a few objects that brighten up periodically. Only about ten are known, and “T Coronae Borealis is the best example of them,” Cooke mentions.
An impending explosion can be gauged not only from the fact that “time is up”, but also from other physical evidence. About a year before this white dwarf becomes nova, it fades out for about a year. And it exactly started in March 2023, which is why astronomers think it will become new by the end of September, Cooke outlines.
Explosive duo
A nova is a phenomenon that requires two stars to form. In a binary star system, two stars orbit each other, a white dwarf and a red giant. A white dwarf is a real dwarf from the point of view of stars – it has the mass of our Sun, but a diameter about a hundred times smaller. So all of its mass is concentrated in a small space, which does interesting things to its surroundings.
When a red giant ejects matter in this system, the dwarf’s gravity grabs hold of it and swallows it up. It stores it in the form of hydrogen and helium plasma on its surface, and it usually does this for millennia before it reaches its limit.
When too much of this mass accumulates, its critical mass is exceeded – essentially, it’s very similar to a thermonuclear bomb. And just like her, there will be a massive explosion. But even the smallest star is much larger than the largest man-made puma, so the explosion is so powerful that it can be seen light years away.
T Coronae Borealis is exceptional at the speed at which it turns into a nova. Scientists do not yet know the cause of periodicity. That is why they are so looking forward to its clarification – direct observation can bring them a lot of knowledge.
2024-03-29 08:15:51
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