V838 Monocerotis Light Echo Space Jigsaw Puzzle

V838 monocerotis was discovered on 6th Januay 2002 by Australian amateur astronomer N.J. Brown who was looking for novas, or new stars, by comparing photographs of the same piece of sky taken on different nights. He noticed a new object in the direction of the Monoceros constellation, named after the Greek word for Unicorn. Brown reported his finding to the International Astronomical Union's Central Bureau for Astronomical Telegrams who, in turn, sent out the details to a select number of astronomers across the world to obtain confirmation of the finding. From previous photographs of the same strip of sky, they were able to work out that the nova's outburst began on 1st January 2002.

Over the next few weeks, V838 monocerotis exhibited typical behaviour of a nova, slowly fading after its initial brightness. However something dramatically different happened in February 2002. In the space of one day, V838 monocerotis increased in its btrightess by around 10,000 times, from visual magnitude 11-12 to magnitude 6.5. At its most luminous, V838 monocerotis was over 600,000 times as bright as our Sun and believed to be one of the brightest stars in the Milky Way galaxy.

At this stage the people who run the Hubble telescope became very interested. After another few weeks of fading back down to visual magnitude 9, V838 monocerotis gave a final burst of brightness up to visual magnitude 7.5 over a period of a few days in March 2002.

It was announced on 25th March 2002 that the first detection of what is called a light echo was made on 17th February 2002 Only two light echoes have been detected from novae before - the last in 1936 and a previous one in 1901. The light echo is formed by light being relflected by surrounding dust and arriving at the observer some time after the initial burst of light. V838's light echo gave the illusion of expanding at faster-than light speeds.

It has been calculated that V838 monocerotis is about 20,000 light years from Earth, very near the outer edge of the Milky Way. What caused the sudden and huge outbursts of light is still a bit of a mystery. A number of different theories exists, including the collision of one larger star with a smaller star. Another theory is that V838 monocerotis may have swallowed one of its giant planets. If a planet had entered V838 monocerotis' atmosphere the friction nd kinetic energy would heat the star's envelope enough to cause deuterium fusion which would result in very fast expansion. The two subsequent increases in brightness may have occurred when other planets were engulfed by the expanded envelope.

Whatever the cause may have been, one thing is for certain - V838 monocerotis and its light echo were among the most marvellous, rare and beautiful happenings to have been observed in our ever-enthralling universe.