Trifid Nebula

The Trifid Nebula (catalogued as Messier 20 or M20 and as NGC 6514) is an H II region in the north-west of Sagittarius in a star-forming region in the Milky Way's Scutum–Centaurus Arm.<ref name=Cambresy11> Template:Cite journal</ref> It was discovered by Charles Messier on June 5, 1764.<ref>Messier 20</ref> Its name means 'three-lobe'. The object is an unusual combination of an open cluster of stars, an emission nebula (the relatively dense, reddish-pink portion), a reflection nebula (the mainly NNE blue portion), and a dark nebula (the apparent 'gaps' in the former that cause the trifurcated appearance, also designated Barnard 85). Viewed through a small telescope, the Trifid Nebula is a bright and peculiar object, and is thus a perennial favorite of amateur astronomers.<ref name="Science Daily">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

The most massive star that has formed in this region is HD 164492A, an O7.5III star with a mass more than 20 times the mass of the Sun.<ref name=Rho04> Template:Cite journal</ref> This star is surrounded by a cluster of approximately 3100 young stars.<ref name=Kuhn15> Template:Cite journal</ref>

Characteristics

The Trifid Nebula was the subject of an investigation by astronomers using the Hubble Space Telescope in 1997, using filters that isolate emission from hydrogen atoms, ionized sulfur atoms, and doubly ionized oxygen atoms. The images were combined into a false-color composite picture to suggest how the nebula might look to the eye.

The close-up images show a dense cloud of dust and gas, which is a stellar nursery full of embryonic stars. This cloud is about Template:Val away from the nebula's central star. A stellar jet protrudes from the head of the cloud and is about Template:Val long. The jet's source is a young stellar object deep within the cloud. Jets are the exhaust gasses of star formation and radiation from the nebula's central star makes the jet glow.

The images also showed a finger-like stalk to the right of the jet. It points from the head of the dense cloud directly toward the star that powers the Trifid nebula. This stalk is a prominent example of evaporating gaseous globules, or 'EGGs'. The stalk has survived because its tip is a knot of gas that is dense enough to resist being eaten away by the powerful radiation from the star.

In January 2005, NASA's Spitzer Space Telescope discovered 30 embryonic stars and 120 newborn stars not seen in visible light images.

It is centered about Template:Val from Earth. Its apparent magnitude is 6.3.

Details and features

• Trifid.nebula.arp.750pix.jpg

  The Trifid Nebula. The outlined area is enlarged right.

• Trifid.nebula.jet.arp.750pix.jpg

  Hubble image of a stellar jet in the Trifid Nebula.

• Cross-fade video comparing views of the Trifid Nebula in visible and infrared light.ogg

  This video sequence compares a new view of the Trifid Nebula in infrared light, from the VVV VISTA survey with a more familiar visible-light view from a small telescope.

• Triffid Nebula.jpg

  The Trifid nebula.

• Trifid Nebula Upclose.jpg

  Trifid Nebula close-up

• Trifid Widefield.jpg

  Widefield image of the Trifid Nebula next to Lagoon Nebula

• Ssc2005-02a.jpg

  Trifid Nebula seen at different wavelengths

See also

• List of Messier objects
• List of nebulae
• Messier object
• New General Catalogue
• Islands (King Crimson album), which uses an image of the nebula as its cover

External links

• New Views of a Familiar Beauty, Spitzer IR Trifid discoveries
• Messier 20, SEDS Messier pages
• Search results for 'Trifid Nebula' at ESA/Hubble
• {{#invoke:citation/CS1|citation

|CitationClass=web }}

• Template:Sky-Map.org
• Trifid Nebula – Messier 20 at Constellation Guide