Exploding star could wipe out life on earth

Astronomers have found evidence that a white dwarf star is increasing in mass and could explode, releasing enough radiation to destroy life on earth. Worryingly, the same study found that the star system is much closer to our planet than previously thought.

T Pyxidis is a binary system consisting of two very close stars: one similar to our own Sun and a much denser white dwarf. The Sun-like star is feeding gas to the white dwarf, triggering cataclysmic nuclear (or nova) explosions at approximately 20-year intervals. These novae had been recorded between 1890 and 1967, but none has been noted since, suggesting that T Pyxidis (above) is at least 20 years overdue for its next explosion.

The crucial question for earthlings is whether the white dwarf is increasing in mass because of the gas it is receiving, or whether the continual explosions mean its mass is falling. As Space Daily explains in considerably more detail, this is because a continually enlarging white dwarf in this kind of binary system will result in a Type Ia supernova: instantaneous gravitational collapse and a nuclear detonation equivalent to twenty billion, billion, billion megatons of TNT.

US astronomers from Villanova University, Philadelphia, say their readings, taken from the International Ultraviolet Explorer satellite, confirm that the white dwarf is indeed increasing in mass. Furthermore, the star is much closer to us than previously thought: within 3,260 light-years away, or 1,000 parsecs.

An explosion of this kind occurring this close to earth would emit so much gamma radiation that it would totally destroy the ozone layer, leaving us totally exposed to the Sun's devastating ultraviolet radiation.

But don't panic: Robin Scagell, vice-president of the UK's Society for Popular Astronomy, told the Daily Telegraph: "The star may certainly become a supernova soon - but soon could still be a long way off so don't have nightmares." ·