Astr111 Photography Projects, Fall 2009

Cocoon Nebula, Neil Patterson

This beautiful masterpiece is a stellar nursery - stars are forming as the material in this gas cloud collapses on itself. The bright star we see just to the right of center is providing most of the light in this nebula, and we see the effects of this light exciting the cloud of hydrogen gas which surrounds this star - the beautiful red color. This central star is around 100,000 years old - a baby as far as stars are concerned. If the star were older it would be more likely that the dust and hydrogen would have blown farther away from the star, thus leaving a star or star cluster, with no hydrogen left to turn red and no dust left to obscure the areas in the nebula which appear dark in these pictures. This nebula is 4000 light years away and the pink area we can see is approximately 10.5 light years across. This nebula is called the Cocoon Nebula because it is at the end of a long starless trail, thus being reminiscent of a worm that has formed a cocoon at the end of a trail it has eaten in a leaf.

The Cocoon Nebula (ic5146) is a giant cloud of gas illuminated by light from stars within them. The blue light at the boundaries of the nebula is light reflected off dust behind the extremely bright star at its center. The area around immediately around and to the right of the nebula is darker and shows few stars than the area left and upward from the nebula (click picture to see this picture). This is because the dust cloud that the nebula is part of is shrouding the stars behind it, thus only the stars in front of the dust cloud are visible to the right of the nebula, whereas a greater depth of stars is visible to the left because there is no dust cloud shrouding stars which are farther away. Other stars may continue to form within this nebula and perhaps other nebulae will form at other points along this swath of dust.

References:

http://loke.as.arizona.edu/~ckulesa/research/overview.html

The Cosmic Cocoon: IC 5146 by Tom V. Davis

http://www.universetoday.com/2008/07/07/the-cosmic-cocoon-ic-5146-by-tom-v-davis/

Astronomy Picture of the Day, March 5, 2009:http://apod.nasa.gov/apod/ap090305.html

Kuhn, Karl F., and Theo Koupelis. In Quest of the Universe. 3rd ed. Sudbury, MA: Jones and Bartlett, 2001. 9. Print.