A pair of white dwarf stars whirling around each other once every 39 minutes will merge and reignite as a helium-burning star in about 37 million years, astronomers said.

These stars have already lived a full life. When they merge, they'll essentially be 'reborn' and enjoy a second life, said Smithsonian astronomer Mukremin Kilic, lead author on the paper announcing the discovery.

Out of the 100 billion stars in the Milky Way, only a handful of merging white dwarf systems are known to exist. Most were found by Kilic and his colleagues at the Harvard-Smithsonian Center for Astrophysics. The latest discovery will be the first of the group to merge and be reborn, astronomers said.

A white dwarf is the hot, dead core left over when a sun-like star gently puffs off its outer layers as it dies. A white dwarf is incredibly dense, packing a Sun's-worth of matter into an Earth-sized ball.

The newly identified binary star is located about 7,800 light-years away in the constellation Cetus. It consists of two white dwarfs, which orbit each other at a distance of 140,000 miles - less than the distance from the Earth to the Moon.

Astronomers said the white dwarf pair isn't heavy enough to go supernova. Instead, they will experience a second life. The merged remnant will begin fusing helium and shine like a normal star once more.