- M 57 (NGC 6720) The Ring Nebula
M 57 is a small, bright planetary nebula located in the constellation Lyra. It was first described in 1779 by Antoine de Darquier de Pellepoix. He described it "as large as Jupiter and looks like a fading planet", a description that led to this type of object being called a "planetary nebula". Charles Messier was aware of Pellepoix's discovery and observed it himself in that same year.
M 57 is probably the best-known planetary nebula. It lies at an estimated distance of 2300 LY and has a physical diameter of approximately 0.9 LY. Although visually small (visual diameter 86 × 62 arc-sec), it is relatively bright (visual magnitude 8.8) and can be easily seen in a small telescope. While the central star has a visual magnitude of only 15.8, it has a very high temperature and its ultraviolet radiation ionizes the surrounding shell of gases. The red components seen along the outer edge of the nebula are due to Hα emissions, while the more diffuse blue-green central portion is due to OIII and Hβ emissions. In long-exposure images, a larger shell of glowing gas surrounding the main nebula can be detected (this feature does not appear in my image).
This image was created by combining individual images acquired in the red, green and blue spectral bands. Since the nebula is relatively bright, I did not need to acquire long-exposure narrow-band images in the Hα, Hβ and OIII bands to produce this image.
|
Return to SOCO Image Gallery