The Trifid Nebula (catalogued as Messier 20 or M20 and as NGC 6514) is an

H II region An H II region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light year ...

in the north-west of Sagittarius in a

star-forming region Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"— collapse and form stars. As a branch of astronomy, star formation inclu ...

in the Milky Way's Scutum–Centaurus Arm. It was discovered by

Charles Messier Charles Messier (; 26 June 1730 – 12 April 1817) was a French astronomer. He published an astronomical catalogue consisting of 110 nebulae and star clusters, which came to be known as the ''Messier objects'', referred to with th ...

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 tens 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, and ...

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

s, an

emission nebula An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emission n ...

(the relatively dense, reddish-pink portion), a

reflection nebula In astronomy, reflection nebulae are interstellar cloud, clouds of Cosmic dust, interstellar dust which might reflect the light of a nearby star or stars. The energy from the nearby stars is insufficient to Ionization, ionize the gas of the nebu ...

(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 ...

(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 (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

, the Trifid Nebula is a bright and peculiar object, and is thus a perennial favorite of amateur astronomers. 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 The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies a ...

. 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 (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

in 1997, using filters that isolate emission from

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

atom Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished fr ...

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

ized

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

atoms, and doubly ionized

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

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 Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"— collapse and form stars. As a branch of astronomy, star formation inclu ...

full of embryonic stars. This cloud is about away from the nebula's central star. A

stellar jet An astrophysical jet is an astronomical phenomenon where outflows of ionised matter are emitted as extended beams along the axis of rotation. When this greatly accelerated matter in the beam approaches the speed of light, astrophysical jets becom ...

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 agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003, that was deactivated when operations ended on 30 January 2020. Spitzer was the third space telescope dedicate ...

discovered 30 embryonic stars and 120 newborn stars not seen in

visible light Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm ...

images. It is centered about from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. Its

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

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 close-up File:Trifid Widefield.jpg, Widefield image of the Trifid Nebula next to Lagoon Nebula File:Ssc2005-02a.jpg, Trifid Nebula seen at different

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

References

External links

New Views of a Familiar Beauty
Spitzer IR Trifid discoveries

SEDS Messier pages
Search results for 'Trifid Nebula'
at ESA/Hubble * *
Trifid Nebula – Messier 20
at Constellation Guide {{Sky, 18, 02, 23, -, 23, 01, 48, 9000 Articles containing video clips Carina–Sagittarius Arm Discoveries by Charles Messier H II regions Messier objects NGC objects Sagittarius (constellation) Star-forming regions 17640605

Characteristics

Details and features

See also

References

External links