Star's Death Could Kill All Life on Earth

Shaun found this article in Cosmos online. A spectacular, rotating binary star system is a ticking time bomb, ready to throw out a searing beam of high-energy gamma rays – and Earth may be right in the line of fire. Astronomers at the University of Sydney, in Australia, first discovered the star system eight years ago in the Constellation Sagittarius. One member of the pair is a highly unstable star known as a Wolf-Rayet, thought to be the final stage of stellar evolution to precede a cataclysmic supernova explosion. When it finally explodes as a supernova, it could emit an intense beam of gamma rays [which would be aimed right at Earth]. The pair of stars is only 8,000 light-years from Earth, just one quarter of the way to the centre of the Milky Way. WR 104 has been observed emitting a vast plume of heated dust and gas, billowing out in a spiral as the stars rotate once every eight months. Viewed from Earth, the rotating tail appears to be laid out on the sky in an almost perfect spiral. It could only appear like that if we are looking nearly exactly down on the axis of the binary system. This means we are peering down the barrel of the gun, as when binary supernovae go off, all their energy is focussed into a narrow beam of wildly destructive gamma ray radiation that emanates (both up and down) from the poles of the system. A 2005 study showed that a gamma-ray burst originating within 6,500 light-years of Earth could be enough to strip away the ozone layer and cause a mass extinction. There is evidence that gamma ray bursts have swept over the planet at various points in Earth's history with a devastating effect on life.

Shaun commented: "Curtain Call and Last Light all rolled into one!" Both short stories by Saunders have been read on BMU (both are available in the show's story archives and in his book Navigating the New World)