NN Serpentis is a close binary star consisting of a red dwarf - a cool star about one-tenth the size of the Sun - orbiting a white dwarf. The two stars orbit each other very closely, but would originally have been much farther apart. They complete an orbit in 3 hours and 7 minutes. Astronomers have found that at least two gas giant planets orbit in this unlikely system; one is about 1.6 times more massive than Jupiter, and the other is nearly six times more massive than Jupiter.