Researchers at the University of Warwick have enlisted a world wide team of amateur / semi-professional astronomers to keep watch on one of the fastest spinning white dwarf stars ever found. The star is long overdue for a major eruption that will increase its brightness a thousand fold.

The University of Warwick researchers, led by Dr Boris Gänsicke, first discovered the star in 2005.  Known as HS2331+3905, it is 260 light years away in the constellation of Andromeda. It belongs to the class of objects called white dwarfs, which are the burnt out cores of  stars like our Sun. HS2331+3905 is roughly the size of the Earth, but weighs about 170000 times more. While the Earth rotates around its axis once per day, HS2331+3905 does so in only 67 seconds, and its surface is pulsating every five minutes. As if that wasn't dramatic enough the researchers have  discovered that it sits in particularly turbulent surroundings that should cause it to erupt once every ten to twenty years, increasing in brightness a thousand fold.  The next such eruption is decades overdue and could happen at any time.

The white dwarf is slowly stripping material from a nearby small companion star that is orbiting around it. That material is building up in an increasingly hot disc surrounding the white dwarf. When the temperature of the disc reaches a critical value, the equivalent of  a pressure valve opens and pours the hot material onto the surge of the White Dwarf. During this eruption, the star will brighten by a thousand fold for a month or two, and then slowly fade into oblivion. These cataclysmic events  should happen roughly every few decades but the Warwick team have now been able to piece together observation records for that part of the sky stretching back to the 1950's which show no sign of an eruption over that period.

When the eruption does come it will obviously be a dramatic event for that star system, but it will also catapult it from its usual dim state into the reach of everybody equipped with a pair of binoculars. The University of Warwick researchers have thus recruited a team of gifted amateur astronomers to keep watch on the star and sound the alert if they see a sign of brightening of HS2331+3905. Once this happens, the astronomers will swing their large telescopes on the ground and in space to study the eruption in all details. One of that network of dedicated amateurs is  Gary Poyner in Birmingham who specialize in observing variable stars. He owns a number of sophisticated telescopes and in 2000 he was awarded the British Astronomical Steavenson Award  for "Outstanding contribution to Observational Astronomy". He said:

"The prospect of catching this object undergoing a rare outburst, is motivation enough for amateur observers like myself to continue monitoring the field on every possible occasion.  Although too faint to see whilst in it's quiescent state, the long periods of looking at 'empty space' will eventually be rewarded once HS2331+3905 finally undergoes the outburst which will cause a ripple of excitement though both amateur and professional astronomical communities alike".

Additional pictures 

 

For further information please contact:        

Dr Boris Gänsicke, Department of Physics 
University of Warwick   02476 574741  
Mobile 07901 875177  
Boris.Gaensicke@warwick.ac.uk

Gary Poyner   0121 605 3716
garypoyner@blueyonder.co.uk
http://www.garypoyner.pwp.blueyonder.co.uk/varstars.html

Peter Dunn, Press and Media Relations Manager,
Communications Office, University of Warwick,  
024 76 523708 or 07767 655860
email: p.j.dunn@warwick.ac.uk