February 13, 2013
New Image Shows Beauty Of Dark Nebula Against A Bright Sky
Lee Rannals for redOrbit.com - Your Universe Online
A new image released by the European Space Observatory (ESO) illustrates the bright star cluster NGC 6520, located in one of the richest star fields in the sky.
Astronomers using ESO's La Silla Observatory in Chile took advantage of the Wide Field Imager on the telescope to snap the image.
The image not only shows off NGC 6520, but also its neighbor, the strange dark cloud known as Barnard 86. These two cosmic objects sit inside millions of glowing stars in the brightest part of the Milky Way.
They are part of the constellation Sagittarius, or The Archer, which resides in the Large Sagittarius Star Cloud. The stars that help to ignite this region in the sky also help emphasize the blackness of dark clouds like Barnard 86. In the image, the dark cloud can clearly be seen, appearing in an almost gecko-like shape.
Barnard 86 is a dark nebula known as a Bok globule, and was first described by astronomer Edward Emerson Barnard as "a drop of ink on the luminous sky." This astronomer not only discovered Barnard 86, but also found and photographed numerous comets, dark nebulae, and one of Jupiter's moons. He was the first astrophotographer to use long-exposure photography to look at dark nebulae.
Barnard 86 sits in the foreground of the image, despite appearing as if it was a break in the stars, showing off a blacker sky behind it. This dark cloud is made up of small dust grains that block starlight, and make the region appear opaque.
Astronomers believe Barnard 86 formed from the remnants of a molecular cloud that collapsed to form the nearby star cluster NGC 6520.
NGC 6520 is an open star cluster that contains hot stars that glow bright blue-white. These types of clusters usually contain a few thousand stars that all formed at the same time. Clusters like this usually live short lives, before drifting apart.
Because of the incredible number of stars in this area, astronomers have a difficult time trying to learn about it. NGC 6520 is believed to be about 150 million years old, and both it and Barnard 86 sit about 6,000 light-years away from the Sun.
In August last year, redOrbit reported about another image released of the Pipe Nebula, another dark nebula. In this region, you can spot more than a dozen tiny blue, green and red strips, which are asteroids, chunks of rock and metal that are orbiting the sun. The entire Pipe Nebula is comprised of Barnard 59, 65, 67 and 78. With little light pollution, and clear skies, the nebula can be seen with the naked eye at southern latitudes.