M39 is an open star cluster. It is composed of about 30 stars that are relatively spread out. Open clusters are generally composed of younger stars, and the stars of M39 are thought to be about 300 million years old, much younger than our own sun. M39 lies about 800 light years away from earth, which is fairly close as far as astronomical objects go. It is located near the constellation Cygnus.
This image of M39 is a color filter image, utilizing clear, red, blue, and green filters. There are several bright bluish-white stars towards the center; which are more luminous than the others. These brighter stars also have the highest mass and temperature in the cluster.The other stars that appear more red or green are less luminous, massive, and hot. The spread out nature of the open cluster is visible in this picture. Using a frame that is 21 arcminutes wide, we can observe a span 5 lightyears across of M39.
Nemiroff, Robert, and Jerry Bonnell. Astronomy Picture of the Day. Ed. Phillip Newman. NASA, 12 Apr. 2009. Web. 6 Dec. 2010. <http://antwrp.gsfc.nasa.gov/apod/ap090412.html>.
Leach, Sid. M39. Apr. 2006. Web. 6 Dec. 2010. <http://www.sidleach.com/m39.htm>.
|Right Ascension (J2000)||21:32|
|Filters used||blue(B), green(V), red(R), and clear(C)|
|Exposure time per filter||300 in V and B, 60 in R and C|
October 28, 2010 (V)