The white dwarf RS-Ophiuchi turns out to be one of the most efficient particle accelerators in the universe. A nova accelerated protons and heavy atomic nuclei from the remnants of the star to their highest theoretically possible energies, determined, as a team led by Alison Mitchell from the University of Erlangen-Nuremberg. The high-energy radiation emitted by the nova, together with computer models, showed that the particles accelerated by the explosion had several hundred times more energy than previously observed novae, Reports the team in »Science«, The result sheds light on why some novae emit gamma rays and suggests that such periodic novae are an important source of high-energy cosmic rays.