Get ready for a “new” star to appear in the night sky. Not really new, of course, but a star now below the limit of visibility to the naked eye is gearing up for an outburst that will bring it into view with the naked eye for the first time since the 1940s.
Such a star is called a nova, Latin for “new”. The star, T Coronae Borealis, actually consists of two stars: a red giant and a white dwarf. The white dwarf is a dense star core about the size of the Earth and its gravity pulls gas away from the red giant. This gas collects on the white dwarf’s surface before exploding in a thermonuclear explosion, causing the star to temporarily brighten. Eventually it returns to normal and the cycle repeats.
In the case of T Coronae Borealis, historical observations show that it explodes approximately every 80 years. Astronomers expect it to blow anytime between now and September. The chart shows the view looking east from London at around 22.00 BST this week, and indicates the location to watch. When it erupts, the star is expected to reach the same brightness as Alphecca, the brightest star in its home constellation.
