Astr112 Photography Projects, Fall 2007

Cocoon Nebula (IC 5146), Megan Hoekstra

The cocoon nebula is an emission nebula located about 4,000 light years away. An emission nebula emits an spectrum of bright emission lines due to the energy that has been absorbed from one or more hot, luminous stars and reemitted by the nebular gas at specific wavelengths. this nebula is also a reflection nebula which is a dense cloud of dust illuminated by a star,and an absorption nebula which absorbs starlight. In 1899 a British clergyman and noted double-star observer Thomas E. Espin recorded the existence of the Cocoon nebula on August 13th, and again two nights later. After viewing the nebula henoticed how well he could see it hestates “faint glow about 8’, well seen each night.” Espin went on describing it as an complicated structure due to the array of colors visable. He noticed In the nebula a newly developing open cluster of stars. Open Star clusters are made from large cosmic gas and dust clouds.

If you look at the photo you can notice a reddish tint this is due to the ionized hydrogen gas, this is called a HII region ( Emission nebula). You can also notice a a blue tint this is due to inner stellar dust causing only blue light to go through (reflection nebula). The dark spots are due to the dust blocking the light from the stars behind(absorption nebula). If you look closely to the center of the nebula you can notice the small clusters of stars forming. There are roughly 110 stars as faint as 17th magnitude in the nebula.The linear size of the Cocoon nebula is 14 light years wide by 12 light years long. The Cocoon nebula is a masterpiece which shows just how amazing our God truly is.

References:
Sanqunetti, Doug. Cocoon Nebula
http://www.dougsastro.net/astrophotos/deepsky/CocoonNebula.htm

Freedman, Roger A., and William J. Kaufmann III. Stars and Galaxies Universe. 3rd ed. New York: Clancy Marshall, 2007.