NASA recently published a wonderful image of a distant cosmic cloud, the glowing remains of a dead Sun-like star. The image was acquired by the Hubble Space Telescope (HST), a sophisticated observatory, exploring the cosmos from Earth orbit. The cloud is known as the Necklace Nebula, as it is similar to a necklace in shape. It is technically designated PN G054.2-03.4.
The Necklace Nebula consists of a bright ring, measuring some 19 trillion km across, dotted with dense, bright clumps of gas that resemble diamonds in a necklace.
Studies show that a pair of stars orbiting close together produced the nebula. About 10,000 years ago, one of the aging stars expanded to the point where it swallowed its companion star. The smaller star continued orbiting inside its companion, increasing the giant star’s rotation rate. The stellar giant spun so fast that it expelled a large part of its gaseous envelope into space. Most of the gas streamed along the star’s equator, producing a ring.
The two stars are so closely located, by cosmic standards, being only a few million km apart. They appear as one bright dot in the center of image. The stars are furiously whirling around each other, completing an orbit in just a little more than a day.
The Necklace Nebula is located 15,000 light-years away from Earth. This image was taken on 2 July 2011, applying a camera aboard HST. The colors of the nebula are due to its constituent gases, including hydrogen and oxygen.
References
NASA
www.nasa.gov/
Hubble Site
http://hubblesite.org/
Wikipedia