Astronomical Observatory: Cool Images

Astr110 Photography Projects, Fall 2006

M56, Ben Tameling

M56 is a globular cluster. A globular cluster is a spherical collection of stars that orbits a galactic core. Its shape is spherical because it is tightly bound together by gravity. A globular cluster is much denser than an open cluster. There are around 150 known globular clusters in the Milky Way, while larger galaxies such as Andromeda may have up to 10,000. This particular globular cluster is located in the constellation Lyra in our own Milky Way Galaxy. It was discovered by Charles Messier on January 23, 1779, and is named "M" after him. M56 is 32,900 light years away from Earth.

Notice the beautiful bright center of stars in this picture. The high density of M56 can easily be seen, as it can in most globular clusters. Near the middle it is very bright because that is where there is the highest density of stars, and it slowly gets dimmer and less dense as you look further out, with a brighter star still visible here and there. Overall there are many fainter stars that aren't visible individually, but they can be seen as a glowing globular shape. The angular size of the picture is 3 arc minutes, which corresponds to a linear size of about 28.72 kly (kilo light years), calculated by using the Small Angle Formula.

References:

Frommert, Hartmut. "Messier 56." Seds.org. 9 Dec. 1999. 16 Nov. 2006 <http://www.seds.org/messier/m/m056.html>

"Messier 56." Wikipedia. 22 Oct. 2006. 16 Nov. 2006 <http://en.wikipedia.org/wiki/Globular_Cluster_M56>