Owl Nebula

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Owl Nebula
M97.jpg
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 is a planetary nebula located approximately 2,030 light years away in the constellation Ursa Major.[2] This object is known by the catalogue identifiers Messier Object 97 (M97) and NGC 3587. 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[edit]

References[edit]

  1. ^ a b Kerber, F. et al. (September 2003), "Galactic Planetary Nebulae and their central stars. I. An accurate and homogeneous set of coordinates", Astronomy and Astrophysics 408: 1029–1035, Bibcode:2003A&A...408.1029K, doi:10.1051/0004-6361:20031046. 
  2. ^ a b Stanghellini, Letizia et al. (December 2008), "The Magellanic Cloud Calibration of the Galactic Planetary Nebula Distance Scale", The Astrophysical Journal 689 (1): 194–202, Bibcode:2003A&A...408.1029K, doi:10.1051/0004-6361:20031046. 
  3. ^ a b c d e f Cuesta, L.; Phillips, J. P. (November 2000), "Excitation and Density Mapping of NGC 3587", The Astrophysical Journal 120 (5): 2661–2669, Bibcode:2000AJ....120.2661C, doi:10.1086/316800. 
  4. ^ a b Jones, Kenneth Glyn (1991), Messierś Nebulae and Star Clusters (2nd ed.), Cambridge University Press, pp. 277–279, ISBN 0521370795. 
  5. ^ Clark, Roger Nelson (1990), Visual Astronomy of the Deep Sky, CUP Archive, p. 133, ISBN 0521361559. 
  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.
  7. ^ a b c Guerrero, Martín A. et al. (June 2003), "Physical Structure of Planetary Nebulae. I. The Owl Nebula", The Astrophysical Journal 125 (6): 3213–3221, arXiv:astro-ph/0303056, Bibcode:2003AJ....125.3213G, doi:10.1086/375206. 
  8. ^ Capriotti, Eugene R.; Kovach, William S. (March 1968), "Effective Temperatures of the Central Stars of Planetary Nebulae", Astrophysical Journal 151 (5): 991–995, Bibcode:1968ApJ...151..991C, doi:10.1086/149498. 
  9. ^ Bilíková, Jana et al. (May 2012), "Spitzer Search for Dust Disks around Central Stars of Planetary Nebulae", The Astrophysical Journal Supplement 200 (1): 3, Bibcode:2012ApJS..200....3B, doi:10.1088/0067-0049/200/1/3. 

External links[edit]

Coordinates: Sky map 11h 14.8m 00s, +55° 01′ 00″