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SEPT. 2011

Hubble Offers a Dazzling View of the Necklace Nebula

The Necklace Nebula

The Necklace Nebula:
With pearls of glowing gas

ASun-like star's last gasps have caught the eye of astronomers. They used the Hubble Space Telescope to view the Necklace Nebula, so-called because of its resemblance to a piece of glittering jewelry.

The nebula consists of a bright ring, measuring 12 trillion miles wide and dotted with pearls of glowing gas. The object is the glowing remains of an ordinary, Sun-like star, called a planetary nebula.

What's in a name?

section of the Necklace Nebula

Necklace Nebula:
A zoomable view

promo image for the nebula gallery

A nebula gallery

The planetary nebula name is a misnomer because these objects have nothing to do with planets. They acquired their name more than 100 years ago when astronomers looking through small, crude telescopes saw them as compact, round, green-colored objects that looked like the planet Uranus.

A planetary nebula forms when a dying star expels its outer layers of material into space after it runs out of fuel to sustain nuclear reactions in its core. Our Sun will undergo a similar process, but not for another 5 billion years. Planetary nebulas fade gradually over tens of thousands of years. The hot remains of the star's core will eventually cool off for billions of years as a white dwarf.

Going out in style

Astronomers have used Hubble to collect a rich assortment of planetary nebulas. Many of them, including the Cat's Eye, the Hourglass, the Helix, and the Spirograph, have names that describe their shapes. Planetary nebulas are like snowflakes: No two are exactly alike.

Several ideas explain the diverse shapes. One idea is that some stars eject their material several times at the end of their lives. Another idea is that gravitational interactions with companion stars in two-star systems create some of the intricate shapes.

The unique shapes are a work of art that everyone can appreciate.


The Star Witness

brings you "tele-scoops" from the Hubble Space Telescope