M27 (Dumbbell Nebula)

Constellation: Vulpecula

Distance: 1200 Light Years

M27 was the first "planetary nebula" ever discovered (by Charles Messier in 1764). The term "planetary nebula" is a misnomer, attributed to astronomers in the late 1700s (particularly William Herschel) who described these objects as resembling planets in when viewed through their early telescopes. These objects form at the end of the life of intermediate size stars (about 1 to 10 times the mass of our Sun, which is expected for form one at the end of its life). At this stage, the star swells into a red giant, then eventually collapses as it burns through its fuel, ejecting its outer layers into space. The small collapsed core (now called a white dwarf) produces extensive radiation which illuminates the previously ejected gases, often in brilliant colors.

John Herschel compared the telescopic view of M27 to a dumbbell, resulting in its nickname. The small white dwarf can be seen at the center. The teal color which composes most of the center of the nebula results from doubly ionized oxygen, which emits light at wavelengths around 500nm..