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First, Some Background Information
Captured through the lenses of the Hubble space telescope, the Eagle Nebula (IC 4703) looks like the bird of prey ready to swoop down on its victim. It became an object of curiosity when the Hubble Space Telescope released photographs of large columns of interstellar gas and dust within the nebula called the Pillars of Creation.
IC 4703 is an emission nebula and made up of clouds of ionized gas emitting ultraviolet rays. An emission nebula is generally categorized into planetary nebulae, where a dying star sheds its outer gases, which are ionized by the star’s hot core, and H II regions–stellar nurseries, where young stars are formed from within the clouds of interstellar dust and gases and emits ultraviolet radiations to ionize them. IC 4703 is an H II region with a star cluster catalogued under Messier Object 16, and together they are called the Eagle Nebula.
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- Constellation: Serpens
- Radius: 70 x 55 light years
- Absolute magnitude: -8.21
- Right Ascension: 18 hours 18 minutes 48 seconds
- Declination: -13 degrees 49’
- Distance: 7,000 light years
- Apparent Magnitude: +6.0
- Apparent dimensions: 7.0 arcmins
- Also known as: NGC 6611, Gum 183, Sharpless 49, RCW 165
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IC 4703 is a star-forming nebula. The nebula’s dense cloud of interstellar gas and dust is the breeding ground of a cluster of young stars. The associated M16 star cluster is around 5.5 million years old and was first discovered by Jean-Philippe Loys de Chéseaux in 1745. The H II region with M16, was discovered by Charles Messier in 1764.
Interestingly, the Swiss astronomer and mathematician Loys de Chéseaux described only the star cluster in his records in 1745. At the time Charles Messier was around 15 years old.
Twenty years later, the French astronomer Messier described this star cluster as “A cluster of small stars, enmeshed in a faint glow, near the tail of Serpens, at little distance to the parallel of Zeta of this constellation; with an inferior telescope this cluster appears like a nebula.' (diam. 8')"1, thus suggesting a star-forming nebula. He cataloged the star cluster and numbered it 16.
The nebula was first photographed by the great American observational astronomer Edward Emerson Barnard in 1895 and in 1897 by an amateur astronomer, Isaac Roberts.
Later, in 1908, the nebula, along with the associated M16 star cluster, was added to the Index Catalogue II of nebulae, galaxies and star clusters and was named IC 4703.
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Facts About the Pillars of Creation: Gigantic Columns of Gas and Dust
The “Pillars of Creation" region within the emission nebula was photographed by the Hubble Space Telescope on April 1, 1995. Astronomers Paul Scowen and Jeff Hester of Arizona State University composed this brilliant picture using over 30 different images captured by the space telescope. All images were captured by the Wide Field and Planetary Camera 2 on board of the Hubble. The impressive “pillars" image was declared one of the best space photographs.
In 2007, an observational study suggested that the giant columns of hydrogen gas and dust were destroyed by a stellar explosion – a supernova – some 6,000 years ago, and that the 1995 photograph is actually a ghost image captured by the HST. The nebula is 7,000 light years away from the Earth and hence the giant columns of interstellar gas and dust will appear intact to the space telescope for another 1,000 years. The study also suggested that in 1,000 - 2,000 years, humans will see an unusually bright spectacle when the stellar explosion engulfing the giant pillars will be captured by a space telescope.
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More Interesting Facts
The hottest stars in the M16 star cluster within the emission nebula are ten thousand times brighter than our Sun. Of these, the brightest star in the nebula has an apparent magnitude of +8.24 and can be easily viewed with a good pair of astronomical binoculars.
The giant pillars of gas and dust are 2-3 light years long and the IC 4703, i.e. the entire nebula, is 20 light-years across.
The Eagle Nebula photograph has featured in several sci-fi serials, including Star Trek Voyager, Contact and Babylon 5.
The nebula also appears in popular videos games like Mass Effect 2, a role-playing video game and Freelancer, a space combat simulation game. In Mass Effect 2, there are three missions that take place within IC 4703.
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1 Catalogue of Nebulae and Star Clusters: http://seds.org/messier/xtra/history/m-cat.html#M16
The Eagle has Risen: Stellar Spire in the Eagle Nebula – ESA/Hubble http://www.spacetelescope.org/images/heic0506b/
Messier Object 16/Eagle Nebula - http://seds.org/messier/m/m016.html
Eagle - Emission Nebula: Amazing Space
Eagle Nebula Fast Facts: http://sites.csn.edu/planetarium/enebula.html
Pillars of Creation Toppled By Stellar Blast: http://www.space.com/3154-pillars-creation-toppled-stellar-blast.html
The Eagle Nebula – Public Domain Image/ http://imgsrc.hubblesite.org/hu/db/2005/12/images/b/formats/print.jpg
The Pillars of Creation Region: Credit: NASA, Jeff Hester, and Paul Scowen (Arizona State University)/ http://hubblesite.org/newscenter/newsdesk/archive/releases/2003/34/image/a