Free Astronomy Magazine September-October 2016

16 SPACE CHRONICLES by NASA I n May 2015, a group of amateur astronomers from Germany, Bel- gium and the UK came across a star system that was exhibiting behaviour unlike anything they had ever encountered before. Follow-up observations led by the University of War- wick and using a multi- tude of telescopes on the ground and in space, including the NASA/ ESA Hubble Space Tele- scope, have now re- vealed the true nature of this previously mis- identified system. The star system AR Scorpii, or AR Sco for short, lies in the con- stellation of Scorpius, 380 light-years from Earth. It comprises a rapidly spinning white dwarf, the same size as Earth but containing 200,000 times more mass, and a cool red dwarf com- panion one third the mass of the Sun. They are orbiting one another every 3.6 hours in a cosmic dance as regular as clock- work. In a unique twist, this binary star system is exhibiting some brutal behaviour. Highly magnetic and White dwarf lashes red dwarf with mystery ray SEPTEMBER-OCTOBER 2016