Astr111 Photography Projects, Fall 2005

Whirlpool Galaxy (M51) , Karen Moschenrose

This object is a spiral galaxy, which is a diffuse mass of interstellar dust or gas or both, visible as luminous patches or areas of darkness depending on the way the mass absorbs or reflects incident radiation. The famous Whirlpool Galaxy was one of Charles Messier's original discoveries, found on October 13, 1773. Its companion, NGC 5195, was discovered in 1781 by his friend, Pierre Mechain. The two atmospheres touch each other, and M51 is the dominating member of a small group of galaxies. It is approximately 37 million light years distant, with a visual brightness of 8.4 mag and the apparent dimension of 11x7 arc min. It was the first galaxy where the spiral structure was discovered.

According to scientific understanding currently, the spiral structure is a result of M51's encounter with its neighbor NGC 5195. Due to this interaction, the gas in the galaxy was disturbed and compressed in some regions, resulting in the formation of new young stars. Two supernovas have been discovered in M51 so far, with one found in its companion. The red color shows the nebula contains hot hydrogen gas. Stars when they form are mostly made of hydrogen. In this photo, we see the two bright stars and bright spiraling arms reaching out to the heavens. The estimated angular size you see from the photo is 11 x 7, and the linear size is 75,339.98.

References:
http://www.seds.org/messier/m/m051.html