Astr111 Photography Projects, Fall 2005

M17, Julie Osterink

Discovered by Philippe Loys de Chéseaux in 1745-46, the Omega Nebula M17, also called the Swan Nebula, the Horseshoe Nebula, or the Lobster Nebula, is a star formation region which shines because of the high energy radiation of the young stars, which are hidden in the nebula. There may still be star formation in this nebula and right now there is an estimated 35 stars in this nebula. M17 is easily found by first finding the bright star, Gamma Scuti, and under good conditions, can be seen by the naked eye.

Hot hydrogen gas, which shines from the hottest stars, is the reason for the reddish coloring and the bright region of the nebula is bright white, due to light from hot gases and star reflection off of the dust in the nebula. The dark lanes within the nebula are made up of dust which does not let the red light to be seen, but the dust is hot enough to emit infrared light. The mass of M17 is about 800 times that of the Sun. The distance is 5,000 light years. The linear size of this nebula is 16 light years and the angular size of M17 is 11 arc minutes.

References:
http://www.seds.org/messier/m/m017.html