Stellar 'novae', or explosions in two-star systems where one is a 'white dwarf', produce nearly 75% of the universe's lithium, Spain-based researchers have confirmed. Studies of two-star system 'nova Sagittarii 1015 N.2' revealed unexpectedly large amounts of beryllium-7, an unstable element that decays into lithium. The rest of the lithium is believed to have formed just after the Big Bang.