Wednesday, 6 January 2010

Supernova Star Blast 'Could Wipe Out Earth'

According to American Astronomers, a white dwarf star is growing in mass and could be getting ready to explode in a blast that could wipe out our planet and solar system.  This star is called T Pyxidis  and it is in a binary star system with another star that is like our Sun, and together they form part of our galaxy the Milky Way. Scientists have shown that T Pyxidis is much closer to the Earth than they previously thought, perhaps being only 3260 light years away.

T Pyxidis Image from Hubble Telescope - Wikimedia Commons Public Domain

In galactic terms this makes T Pyxidis a very close neighbour and it is due to explode into a supernova in a blast that would have a force of 20 billion billion billion tons of TNT.  Scientists believe that the blast could strip our vital ozone layer, which is the layer that protects us from deadly space radiation.

This close binary star system that includes T Pyxidis is known as a recurrent nova because the huge white dwarf star experiences thermonuclear or nova explosions in a regular cycle every 20 years.  However, the next expected explosion is overdue by around 44 years, and the experts are not sure why.  The explosions are caused by gases containing large quantities of hydrogen being transferred from the nearby Sun-like star, which raises the question of whether the white dwarf T Pyxidis grow in mass because of this transfer of gasses, or decreases in mass because the continuing thermonuclear explosions expel more mass than it gains from its close stellar companion.

If the white dwarf continues to increase in mass, this could lead to what is known as a Type 1a supernova, as once the mass of the star reaches what is known as the Chandrasekhar Limit it is believed that it will experience an immediate gravitational collapse which will trigger an enormous thermonuclear blast which will completely destroy the binary star system and leave a black hole.

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