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
in the
Milky Way's Scutum-Centaurus Arm.
[
] It was discovered by
Charles Messier on June 5, 1764.
Messier 20
/ref> Its name means 'three-lobe'. The object is an unusual combination of an open cluster
An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, an ...
of star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
s, an emission nebula (the relatively dense, reddish-pink portion), a reflection nebula (the mainly NNE blue portion), and a dark nebula
A dark nebula or absorption nebula is a type of interstellar cloud, particularly molecular clouds, that is so dense that it obscures the visible wavelengths of light from objects behind it, such as background stars and emission or reflection neb ...
(the apparent 'gaps' in the former that cause the trifurcated appearance, also designated Barnard 85). Viewed through a small telescope
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obse ...
, the Trifid Nebula is a bright and peculiar object, and is thus a perennial favorite of amateur astronomers.mass of the Sun
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...
.[
]
This star is surrounded by a cluster of approximately 3100 young stars.[
]
Characteristics
The Trifid Nebula was the subject of an investigation by astronomers using the Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...
in 1997, using filters that isolate emission from hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...
atom
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons.
Every solid, liquid, gas, a ...
s, ionized sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...
atoms, and doubly ionized oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
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
away from the nebula's central star. A stellar jet protrudes from the head of the cloud and is about 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
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeedin ...
's Spitzer Space Telescope discovered 30 embryonic stars and 120 newborn stars not seen in visible light
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...
images.
It is centered about from Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...
. Its apparent magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...
is 6.3.
Details and features
File:Trifid.nebula.arp.750pix.jpg, The Trifid nebula. The outlined area is enlarged right.
File:Trifid.nebula.jet.arp.750pix.jpg, Hubble image of a stellar jet in the Trifid nebula.
File: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.
File:Triffid Nebula.jpg, The Trifid nebula.
File:Trifid Nebula Upclose.jpg, Trifid Nebula Upclose
See also
* List of Messier objects
* List of nebulae
* Messier object
* New General Catalogue
* Wikipedia Project: Astronomical Objects
* The Alternative Factor
"The Alternative Factor" is the twenty-seventh episode of the first season of the American science fiction television series '' Star Trek''. Written by Don Ingalls and directed by Gerd Oswald, it first aired on March 30, 1967.
In the episode, th ...
* Islands (King Crimson album), which uses an image of the nebula as its cover
References
External links
Spitzer IR Trifid discoveries
SEDS Messier pages
Trifid Nebula at ESA/Hubble
*
*
Trifid Nebula at Constellation Guide
{{Sky, 18, 02, 23, -, 23, 01, 48, 9000
Carina–Sagittarius Arm
H II regions
Messier objects
NGC objects
Sagittarius (constellation)
17640605
Articles containing video clips
Star-forming regions