Owl_Nebula
Owl Nebula
Planetary nebula in the constellation Ursa Major
The Owl Nebula (also known as Messier 97, M97 or NGC 3587) is a planetary nebula approximately 2,030 light years away in the constellation Ursa Major.[2] Estimated to be about 8,000 years old,[6] it is approximately circular in cross-section with a 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.[5] The nebula is arranged in three concentric shells, with the outermost shell being about 20–30% larger than the inner shell.[7] The 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.[5]
The nebula holds about 0.13 solar masses (M☉) of matter, including hydrogen, helium, nitrogen, oxygen, and sulfur;[5] all with a density of less than 100 particles per cubic centimeter.[7] Its outer radius is around 0.91 ly (0.28 pc) and it is expanding with velocities in the range of 27–39 km/s into the surrounding interstellar medium.[5]
The 14th magnitude central star has passed the turning point in its evolution and is condensing to form a white dwarf.[7][8] It has 55–60% of solar mass, is 41 to 148 times solar luminosity (L☉),[5] and has an effective temperature of 123,000 K.[9] The star has been successfully resolved by the Spitzer Space Telescope as a point source that does not show the infrared excess characteristic of a circumstellar disk.[10]