Owl Nebula

Template:Short description Template:Planetary nebula 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.<ref name="Stanghellini2008"/> Estimated to be about 8,000 years old,<ref name="calc_age" /> 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.<ref name="CuestaPhillips2000" /> The nebula is arranged in three concentric shells, with the outermost shell being about 20–30% larger than the inner shell.<ref name="Guerrero2003" /> 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.<ref name="CuestaPhillips2000" />

The nebula holds about 0.13 solar masses (Template:Solar mass) of matter, including hydrogen, helium, nitrogen, oxygen, and sulfur;<ref name="CuestaPhillips2000"/> all with a density of less than 100 particles per cubic centimeter.<ref name="Guerrero2003"/> Its outer radius is around Template:Convert and it is expanding with velocities in the range of 27–39 km/s into the surrounding interstellar medium.<ref name="CuestaPhillips2000"/>

The 14th magnitude central star has passed the turning point in its evolution and is condensing to form a white dwarf.<ref name="Guerrero2003"/><ref name="Jones1991"/> It has 55–60% of solar mass, is 41 to 148 times solar luminosity (Template:Lo),<ref name="CuestaPhillips2000"/> and has an effective temperature of 123,000 K.<ref name="Capriotti1968"/> 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.<ref name="Bilikova2012"/>

History

The Owl Nebula was discovered by French astronomer Pierre Méchain on February 16, 1781.<ref name="Jones1991" /> Pierre Méchain was Charles Messier's observing colleague, and the nebula was observed by Messier himself a few weeks following the initial sighting.<ref>Template:Cite journal</ref> Thus, the object was named Messier 97, and included in his catalog on March 24, 1781.<ref name=":0" /> Of the object, he noted:<ref>{{#invoke:citation/CS1|citation |CitationClass=web

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Nebula in the great Bear, near Beta: It is difficult to see, reports M. Méchain, especially when one illuminates the micrometer wires: its light is faint, without a star. M. Méchain saw it the first time on Feb 16, 1781, & the position is that given by him. Near this nebula he has seen another one, [the position of] which has not yet been determined [Messier 108], and also a third which is near Gamma of the Great Bear [Messier 109]. (diam. 2′).

In 1844, Admiral William H. Smyth classified the object as a planetary nebula.<ref name=":0">{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref><ref name="Owl Nebula M97, NGC 3587">Template:Citation</ref> When William Parsons, 3rd Earl of Rosse, observed the nebula in Ireland in 1848, his hand-drawn illustration resembled an owl's head. In his notes, the object was described as "Two stars considerably apart in the central region, dark penumbra round each spiral arrangement, with stars as apparent centres of attraction. Stars sparkling in it; resolvable."<ref>Template:Cite book</ref><ref>Template:Cite book</ref> It has been known as the Owl Nebula ever since.<ref name="Clark1990" /> More recent developments in the late 1900s include the discovery of a giant red halo of wind extended around its inner shells,<ref>Template:Cite journal</ref> and the mapping of the nebula's structure.<ref name="Owl Nebula M97, NGC 3587" /><ref>Template:Cite book</ref><ref>Template:Cite journal</ref>

Observing

Although the Owl Nebula can not be seen with the naked eye, a faint image of it can be observed under remarkably good conditions with a small telescope or 20×80 binoculars. To make out the nebula's more distinctive owl like eye features, a telescope with an aperture 10" or better is required. To locate the nebula in the night sky, look to the southwest corner of the Big Dipper's bowl, marked by the star Beta Ursae Majoris. From there, M97 lies just over 2.5 degrees in the southeast direction towards the star positioned opposite Beta Ursae Majoris in the other bottom corner of the Big Dippers Bowl, Gamma Ursae Majoris; which marks the constellations southwest corner. M97, together with Alpha Ursae Majoris, point the way to Polaris.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Gallery

• The Owl Nebula M97 Goran Nilsson & The Liverpool Telescope.jpg

  HaRGB image of the Owl Nebula M97 from the Liverpool Telescope

• M97rosse.jpg

  Drawing of the Owl Nebula (M97) by Lord Rosse, who gave the name to the planetary nebula. Source: seds.org

• The location of Messier 97 in Ursa Major.png

  Location of M97 in Ursa Major

• M97 3h59m 121923 FINAL.jpg

  The Owl Nebula (also known as Messier 97, M97 or NGC 3587) - 239 x 60 second exposure.

• Outer O-III ring of M97 nebula.jpg

  Outer O-III shell of M97 in a HOO composition

See also

• Messier object
• List of Messier objects
• New General Catalogue
• List of planetary nebulae

External links

• The Owl Nebula @ SEDS Messier pages
• The Owl Nebula at Calar Alto Observatory
• NightSkyInfo.com – M97, the Owl NebulaTemplate:WikiSky
• {{#invoke:citation/CS1|citation

|CitationClass=web }}

• The Owl Nebula (M97) at Constellation Guide
• Messier 97: Owl Nebula at Messier Objects