... The newly discovered example of a ring-shaped planetary nebula is about 15,000 light-years distant. ... Planetary nebulae are created by sun-like stars in a final phase of stellar evolution. But the Necklace Nebula's central star, near the center of a ring strongly tilted to our line of sight, has also been shown to be binary , a close system of two stars with an orbital period of just over a day. ... Those clouds were likely ejected about 5,000 years before the clouds forming the necklace. ...