A planetary nebula is material thrown off by a star that has run out of hydrogen fuel to burn. Planetary nebulas are generally faint objects; none are visible to the naked eye. The first planetary nebula discovered was the Dumbbell Nebula in the constellation of Vulpecula, observed by Charles Messier in 1764 and listed as M27 in his catalogue of nebulous objects. M57 was discovered by Antoine Darquier de Pellepoix in January, 1779 and discovered independently by Charles Messier on January 31, 1779. M57 is a cluster of light between Gamma & Beta Lyrae, discovered when looking for the Comet of 1779, which passed very close. The distance of the M57 is 2.3 kly. This ring nebula shows in the northern hemisphere summer sky.
When we look at M57, we see a ring which has distinctive three colors. Green light of ionized oxygen and nitrogen dominates the color. At the edge of the ring, in the outer region, only the red light of hydrogen can be seen. In the boundary of green and red, we can see yellow. In the middle, there is one blue dot which is a light from a very hot star. It emits ultraviolet light that causes the nebula glow because of the hotness. The distance to this object is estimated to be 2300ly; we find a maximum angular size of 98.69 arcseconds, which corresponds to a linear size of 1.1ly.
Wikipedia. "Planetary Nebula." <http://en.wikipedia.org/wiki/Planetary_nebula>
Frommert, Hartmut and Kronberg, Christine. "Messier 57." <http://messier.seds.org/m/m057.html>
|Right Ascension (J2000)||18:53:35|
|Filters used||B (Blue), R (Red), V (Green)|
|Exposure time per filter||B, V, and R (60s)|
|Date observed||October 26, 2012|