... They have found that a class of variable stars named after their prototype R Coronae Borealis (RCrB), and a related group called 'extreme helium stars' are the products of mergers between pairs of white dwarf stars. ... A merger between a carbon-oxygen white dwarf and a helium white dwarf matched the shrinking helium stars Jeffery had observed with IUE and explained very well the properties of RCrB stars and extreme helium stars. ... email: csj@star.arm.ac.uk . WWW: http://star.arm.ac.uk/~csj/ . ...