The Owl Nebula (Messier 97) is a supernova or planetary nebula approximately 2,030 light years away in the northern constellation Ursa Major. The estimated age of the Owl Nebula is about 8,000 years. It is approximately circular in cross-section with faint internal structure. It was formed from the outflow of material from the stellar wind of the central star as it evolved along the asymptotic giant branch.
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The nebula is arranged in three concentric shells/envelopes, with the outermost shell being about 20–30% larger than the inner shell. A mildly owl-like appearance of the nebula is the result of an inner shell that is not circularly symmetric, but instead forms a barrel-like structure aligned at an angle of 45° to the line of sight.
The nebula holds about 0.13 solar masses of matter, including hydrogen, helium, nitrogen, oxygen, and sulfur; Its outer radius is around 0.9 light years across and it is expanding with velocities in the range of 27–39 km/s into the surrounding interstellar medium.
The 14th magnitude central star, left over from the supernova, has passed an apex of its evolution so is condensing to form a white dwarf.
M108, the Galaxy above the owl nebula, or the Surfboard galaxy, is located in the constellation Ursa Major approximately 46 million light-years away. It is called the Surfboard galaxy because, when viewed with a telescope, it is seen nearly edge-on with no apparent bulge or pronounced core.
There is little evidence of a well-defined spiral pattern in the galaxy, but M108 is classified as a barred spiral galaxy with loosely wound spiral arms. Observations show young star clusters exposed against a mottled and detail-rich background. M108 also contains supershells, which are shells of gas driven by bursts of star formation and resulting supernova explosions. The supershells could also be driven by stellar jets or an infall of gas from outside the galaxy.
At the center of M108 is a supermassive black hole estimated to be 24 million times as massive as the Sun.