Messier 97 (M97), also known as the Owl Nebula or NGC 3587, is a famous planetary nebula located in Ursa Major constellation at a distance of 2030 light years from Earth. M97 occupies an apparent area 3,4 by 3,3 arc minutes, which corresponds to a spatial diameter of 1,82 light years. It was named the Owl Nebula because of its appearance in larger telescopes, which reveal two dark patches that look like the eyes of an owl.
The nebula formed when a dying Sun-like star ran out of hydrogen fuel, collapsed from a red giant to a white dwarf, and ejected its outer envelope. The expelled material is now heated by the radiation of the central white dwarf, producing the nebula’s glow. The nebula has been gradually expanding and will completely disperse into space over the next several thousand years, while the white dwarf will cool and fade away over the next several billion years.
The 16th magnitude central white dwarf (visible in my picture) has about 0,7 solar masses and is between 41 and 148 times brighter than the Sun. When it collapsed, the central star expelled a large amount of matter in two opposing directions, which resulted in the nebula’s owl-like appearance. The two jets of matter are almost aligned with our line sight, but just slightly off. The dust in the jets blocks some of the light of the expanding nebula, giving it the appearance of two dark eyes. The jet pointing in our direction appears as the darker eye, while the one pointing away from us appears slightly fainter.
Messier 97 is one of only four planetary nebulae listed in the Messier catalogue. The other three are the Dumbbell Nebula (M27) in Vulpecula, the Ring Nebula (M57) in Lyra, and the Little Dumbbell Nebula (M76) in Perseus constellation.
The Owl Nebula was discovered by French astronomer Pierre Méchain on February 16, 1781. Méchain reported the discovery to his friend and colleague Charles Messier, who added the nebula to his catalogue.