Owl Nebula

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Messier 97, Owl Nebula
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Owl Nebula
Observation data
(Epoch J2000.0)
Right ascension 11h 14m 47.734s[1]
Declination +55° 01′ 08.50″[1]
Distance 2,030 ly (621 pc)[2]
Apparent magnitude (V) +9.9
Apparent dimensions (V) 3′.4 × 3′.3
Constellation Ursa Major
Physical characteristics
Radius 0.91 ly (0.28 pc)[3]
Notable features Owl-like "eyes" visible through larger telescopes
Other designations M97, NGC 3587, PN G148.4+57.0
See also: Planetary nebula, Lists of nebulae

The Owl Nebula (Messier 97,M97, NGC 3587) is a planetary nebula located approximately 2,030 light years away in the constellation Ursa Major.[2] It was discovered by French astronomer Pierre Méchain on February 16, 1781.[4] When William Parsons, 3rd Earl of Rosse, observed the nebula in 1848, his hand-drawn illustration resembled an owl's head. It has been known as the Owl Nebula ever since.[5]

The nebula is approximately 8,000 years old.[6] It is approximately circular in cross-section with a little visible 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.[3] 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.[3]

The nebula holds about 0.13 solar masses of matter, including hydrogen, helium, nitrogen, oxygen, and sulfur;[3] 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.[3]

The 14th magnitude central star has since reached the turning point of its evolution where it condenses to form a white dwarf.[4][7] It has 55–60% of the Sun's mass, 41–148 times the brightness of the Sun,[3] and an effective temperature of 123,000 K.[8] 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.[9]

See also

References

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  6. Per Guerrero et al. (2003), the age is 12,900 × d years, where d is the distance in kpc. According to Stanghellini et al. (2008), d is 0.621 kpc. Hence, the age is 12,900 × 0.621 ≈ 8,000 years.
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External links

Coordinates: Sky map 11h 14.8m 00s, +55° 01′ 00″[[Category:Orion–]