Eagle Nebula

Eagle Nebula

Published: November 8, 2007, 12:00 am
Updated: March 24, 2009, 12:48 pm
Lead Author: Bryan Mendez
Topics: Nebulae Stars

Eagle Nebula Data 

Object Name: Eagle Nebula, M16, NGC 6611, IC 4703

Object Type: Nebula, Star Cluster, Open Cluster, HII Region

Location: RA: 18 18.8 Dec: -13 47 (2000.0; Galactic Coordinates: l = 16.97, b = +0.80). In the constellation Serpens Cauda, near the border of the constellation Scutum, in the plane of the Milky Way Galaxy, very near the direction of the Galactic Center. Most visible in the sky during June-August.

Object Distance: 7,000 +/- 300 ly (1999A&AS..134..525B)

Object Size: 7.0 Arcmin (Wikipedia), 70 x 55 ly (Wikipedia)

Object Brightness: apparent visual magnitude = 6.4 (Wikipedia), absolute visual magnitude = -8.21 (wikipedia)

Object Description: The Eagle Nebula is a region of active star formation in the Milky Way Galaxy. It is a region in the Galaxy where the interstellar medium is gathered into a cloud of higher than average density. Here the hydrogen gas within the cloud is being ionized by strong ultraviolet radiation from hot, young stars that have newly formed within the cloud itself. Such places are called HII Regions by astronomers (where the HII refers to the ionized state of hydrogen in the cloud). The young stars in the Eagle Nebula form an Open Cluster.

Hubble Space Telescope image inside the Eagle Nebula. Hubble Space Telescope image inside the Eagle Nebula.

Hubble Space Telescope composite image of the Eagle Nebula. (Source: NASA Picture of the Day - NOAO/AURA.)

In a wide-field view of the nebula, it resembles a bird, hence its common name: The Eagle Nebula.

The Eagle Nebula is visible in binoculars as a hazy cluster of stars, the nebula itself is only noticeably visible in photographs with longer-exposure times.

The natural color of the nebula is red, which is true of HII Regions in general. This is due to the predominance of hydrogen gas in the nebula. Ionized hydrogen emits most of its visible light in a specific color of red that arises from the most common electronic transition in hydrogen called H-Alpha.

Perhaps one of the most famous astronomical images of all time is that of the Eagle Nebula taken from the Hubble Space Telescope in 1995. The images depicts the finger-like protrusions from three enormous columns of cooler gas in the central region of the nebula. The central part of the nebula is being evaporated by ultraviolet radiation from the hot, young stars in the central open cluster. The pillars are cooler, more dense parts of the nebula that are resisting the evaporation. Within these pillars are clouds dense enough to begin gravitationally collapsing under their own weight and forming new stars.

Hubble Space Telescope composite image of the " Pillars of Creation" in the central region of the Eagle Nebula. Hubble Space Telescope composite image of the " Pillars of Creation" in the central region of the Eagle Nebula.

Hubble Space Telescope composite image of the "Pillars of Creation" in the central region of the Eagle Nebula. (Source: HubbleSite.)

The 1995 “Pillars of Creation” Hubble image is a false-color image, i.e. the colors in the image are not the natural appearance of the nebula. The colors in the image are used more to illustrate certain features rather than to depict how the nebula would appear to human eyes. Photos are often taken by telescopes using filters to focus on certain parts of the spectrum of light coming from a celestial object. If multiple photos are taken of an object in multiple filters, then the individual images can be combined to create a color image. If the filters used closely match the red, green, and blue channels used to create colors on televisions, video cameras, and computer monitors, then the resulting image will closely match what our eyes might see if we were very close to the celestial object. In the case of the Eagle Nebula, images were taken in two filters in red parts of the spectrum to capture emission from hydrogen and sulfur and a third filter was used in the green part of the spectrum to capture emission from oxygen. The final enhanced color image mapped the green (oxygen) filter to the blue channel, one red (sulfur) filter to the green channel, and the other red (hydrogen) filter to the red channel. The resulting image had a beautiful array of colors depicting the relative mixtures of gaseous elements in different locations. The same color mapping scheme has been used by many amateur astrophotographers and even other astronomers studying the Eagle Nebula.

The “Pillars of Creation” Hubble image of the Eagle Nebula has also entered into the popular culture consciousness through many venues. It was featured in the liner notes of the 2000 Pearl Jam album called Binaural. It has been seen in several science fiction movies and television shows such as Star Trek Voyager, Babylon 5, and Contact. The color scheme used in the image has also been copied in many other science fiction television programs and movies as well as space art depicting the interstellar medium.

Related Topics: Nebulae, Star Clusters, Star Formation

External Links

Image Resources:

HubbleSite Images of the Eagle Nebula
Click images to download original large tiff-format images.
(Source: STScI)
1955_44 1955_44
 

 

HubbleSite Image Tours: Eagle Nebula (Source: HubbleSite)

 

Further Reading

Preview Image

Eagle Nebula - HubbleSite (STScI)

Citation

Mendez, Bryan (Contributing Author); Bernard Haisch (Topic Editor). 2008. "Eagle Nebula." In: Encyclopedia of the Cosmos. Eds. Bernard Haisch and Joakim F. Lindblom (Redwood City, CA: Digital Universe Foundation). [First published November 8, 2007].
<http://www.cosmosportal.org/articles/view/135509/>

 

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