This week we are focusing on what is currently a dark patch in the sky, but won鈥檛 be for much longer. That鈥檚 because a 鈥渘ew鈥� star is expected to appear in the night sky over the next few months.
Of course, the star isn鈥檛 actually new 鈥� it has been around for billions of years. What鈥檚 new is that it will be visible to the naked eye, temporarily, while undergoing an explosive event called a nova.
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The object in question, called T Coronae Borealis 鈥� or the much catchier 鈥渂laze star鈥� 鈥� is actually a binary star system made up of a white dwarf and a red giant orbiting each other. The hungry white dwarf has been stealing hydrogen from its companion star by means of its gravitational pull. 鈥淥nce sufficient material has built up, [it] will reach a critical temperature, igniting hydrogen fusion,鈥� says , an astronomer at the University of Warwick in the UK. 鈥淭his powerful nuclear detonation ejects the gas from the white dwarf surface in a hot, luminous shell. What we then see is the system becoming thousands of times brighter.鈥�
While the exact date this explosion will happen isn鈥檛 known, astronomers have been watching the system and expect it to be soon. After observing a dip in brightness since March 2023, which happens before a nova, they predict it will occur between now and September. Once it explodes, the system will become almost as bright as Polaris, the North Star, for a few days.
The best way to prepare for the event is to get familiar with the patch of sky the star system sits in. T Coronae Borealis is in a small constellation called Corona Borealis. This sits between Bo枚tes and Hercules, two much larger constellations in the northern sky.
The best way to find Corona Borealis is by first finding two stars: Arcturus, which will be high in the south in the northern hemisphere, and Vega, which will be lower in the sky and towards the east. These are the two brightest stars in the northern hemisphere, so they should be easy to see from there. Looking directly between the two, you should spot a horseshoe-shaped group of stars: this is Corona Borealis. From the southern hemisphere, Arcturus will be low in the north-east. If Vega is visible, it will be near the eastern horizon and Corona Borealis will be low in the north-eastern sky.
When it makes its appearance, the 鈥渘ew鈥� star will be the brightest in the constellation, making it hard to miss. It will appear just below and to the left of the main horseshoe shape. This kind of event doesn鈥檛 come around often 鈥� this star system is one of 10 known repeating novae and it explodes roughly every 80 years.
I hope you enjoy watching the sky change. It is a lovely reminder that the stars aren鈥檛 fixed points of light as they seem to be, but dynamic monsters that are growing and evolving.
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