!n the 1920’s, most astronomers thought that all of the universe — the planets, the stars seen with the naked eye and with powerful telescopes, and fuzzy objects called nebulae — was contained within the Milky Way galaxy. Astronomer Edwin Hubble’s discovery that countless galaxies exist beyond our own Milky Way galaxy revolutionized our understanding of the universe and our place within it.
Two Doomed Sun-like Stars
Fast forward to today, the Hubble Space Telescope captured the interaction of two doomed stars that created the spectacular ring adorned with bright clumps of gas—a diamond necklace of cosmic proportions shown above. Fittingly known as the “Necklace Nebula,” this planetary nebula –an interstellar cloud of dust, hydrogen, helium and other ionized gases–is located 15,000 light-years away from Earth in the small, dim constellation of Sagitta (the Arrow).
A pair of tightly orbiting sun-like stars produced the Necklace Nebula, which also goes by the less glamorous name of PN G054.203.4. Roughly 10,000 years ago, one of the aging stars expanded and engulfed its smaller companion, creating something astronomers call a “common envelope.” The smaller star continued to orbit inside its larger companion, increasing the bloated giant’s rotation rate until large parts of it spun outwards into space. This escaping ring of debris formed the Necklace Nebula, with particularly dense clumps of gas forming the bright “diamonds” around the ring.
The pair of stars which created the Necklace Nebula remain so close together—separated by only several million miles—that they appear as a single bright dot in the center of this image. Despite their close encounter, the stars are still furiously whirling around each other, completing an orbit in just over a day.
Hubble previously released an image of the Necklace Nebula, but this new image uses advanced processing techniques to create an improved and fresh view of this intriguing object. The composite image includes several exposures from Hubble’s Wide Field Camera 3.
Image credit: ESA/Hubble & NASA, K. Noll