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A ‘once in a lifetime opportunity’ is heading your way and all you have to do is look up.
Or it might be twice in a lifetime, if you’re lucky.
Sometime between now and September 2024, a ‘new’ star will appear in the sky – but only for a week.
That’s because around 3,000 light-years away, the star system T Coronae Borealis, or T Cr B, is about to explode. When it does, it will become visible to the naked eye here on Earth.
T Cr B last exploded in 1946, meaning some who saw it then could witness it again now – and many more will hopefully be around when it explodes again in another 80 or so years.
Astronomers predict that when it does erupt, it may be as bright as the North Star, Polaris.
As its brightness peaks, it should be visible to the naked eye for several days, and just over a week if you use binoculars before it dims again.
Astronomers at Nasa say the temporary new star will be located in the constellation Corona Borealis, or the Northern Crown, which is a small, semicircular arc near Bootes and Hercules.
Dr Daniel Brown, an associate professor in astronomy at Nottingham Trent University, said: ‘We are in for a treat, being granted a so-called new star in the skies.
‘T Coronae Borealis is actually not a single star but a binary, so two stars orbiting each other.
‘What makes this pair so special is that every so often it increases its brightness immensely to become easily visible to us.’
He said the more massive star in the pair is a white dwarf, which ‘can pack roughly the same mass as our Sun in a volume as large as Earth’.
Its companion, an ageing red giant, has expanded and is steadily dumping its material on to the white dwarf.
Jessica Lee, astronomer at Royal Observatory Greenwich said: ‘T Coronae Borealis is normally a very faint star with a magnitude of around 10, which means you’d need a pair of binoculars to see it.
‘However this star is actually a binary system, which means it’s a pair of stars orbiting each other. The system consists of a white dwarf star and a red giant star.
‘As the red giant star swells up and sheds its outer layers, the white dwarf star will pull this material onto itself. This material causes the star to heat up and the build up in heat eventually causes a “nova” or explosion on the surface of the star. This isn’t a supernova, so the whole star isn’t exploding or dying, but a temporary brightening of the star.’
Dr Brown said: ‘Every 80 years or so it [the white dwarf] gathers enough material so that it ignites in a thermonuclear explosion, boosting its brightness incredibly.
‘For T Coronae Borealis, the time is up for another such explosion, taking its brightness from 11mag – just about visible with binoculars in a dark sky – to a whopping 2mag – comparable to the stars in the Plough and easy to spot with the naked eye, in even light polluted skies.’
Following the outburst, T Coronae Borealis will be become the brightest star in the constellation of Corona Borealis before gradually dimming after several days.
Dr Brown said the constellation can be seen in the UK.
‘In the UK over the summer months you can continuously see the constellation of Corona Borealis and where the Nova T CrB is located which is ideal to follow the predicted possible nova outbreak,’ he said.
‘At the start of the summer as the Sun sets late at night, the region of interest is already at its highest due South. It remains above the horizon until the Sun rises again.
‘Towards the end of summer it will move further west and is already lower in the sky at the start of the night, which means it will set by midnight. But that gives us loads of hours of good observing to spot the nova.’
Ms Lee said the Corona Borealis constellation can be spotted by following the Plough’s handle in a curve down towards the star Arcturus, the brightest star in the constellation of Bootes.
‘If you’re trying to find it it’s between Arcturus, a much brighter star in the constellation of Boötes, and Vega, a much brighter star in the constellation of Lyra,’ she said.
‘When the nova does occur the star will increase in brightness to such an extent it will be visible to the naked eye for about a week before dimming again, so it’s worth looking for while you can!
‘A star gazing app might help you out as even once it’s brightened it won’t be the brightest star in the sky by any means, and you’ll need dark and clear skies to spot it.’
Historical reports show the nova was spotted in 1946, but it was first ‘discovered’ in 1866 by Irish astronomer John Birmingham. However, reports also mention seeing the nova in 1787 and 1217.
Observations of T Cr B show that the nova acted erratically in the lead-up to its eruption, and its activity over the past decade suggests its gearing up for an explosion.
It’s definitely one to keep an eye on.
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