The Trapezium, or Orion Trapezium Cluster is a tight open cluster of stars that lies within the heart of the Orion Nebula, in the constellation of Orion. It was discovered by Galileo Galilei in 1617, who sketched three of the stars (A, C, D) but somehow missed the surrounding nebulosity. The fourth component (B) was identified by several observers in 1673, and several more components were discovered later, for a total of eight by 1888. Subsequently several of the stars were determined to be binaries. The J2000. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... This article or section does not adequately cite its references or sources. ... Orion (IPA: ), a constellation often referred to as The Hunter, is a prominent constellation, perhaps the best-known and most conspicuous in the sky. ... Equatorial Coordinates Right ascension (abbrev. ... In astronomy, declination (abbrev. ... A light-year, symbol ly, is the distance light travels in one year: exactly 9. ... Stellar parallax motion The parsec (symbol pc) is a unit of length used in astronomy. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... In astronomy, the solar mass is a unit of mass used to express the mass of stars and larger objects such as galaxies. ... A light-year, symbol ly, is the distance light travels in one year: exactly 9. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... The Pleiades is one of the most famous open clusters. ... The Pleiades is one of the most famous open clusters. ... STAR is an acronym for: Organizations Society for Telescopy, Astronomy, and Radio, a non-profit New Jersey astronomy club. ... The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated south of Orions Belt. ... This article or section does not adequately cite its references or sources. ... Orion (IPA: ), a constellation often referred to as The Hunter, is a prominent constellation, perhaps the best-known and most conspicuous in the sky. ... KDFSAJFKASJDKFJASDKLJFDKLASJFLKJASKLFJLAKSJFLKSJALFKJSKLJFto the Sun-centered solar system which Galileo supported. ... Events Change of emperor of the Ottoman Empire from Ahmed I (1603-1617) to Mustafa I (1617-1623). ... 1673 (MDCLXXIII) was a common year starting on Sunday of the Gregorian calendar (or a common year starting on Wednesday of the 10-day slower Julian calendar). ... Year 1888 (MDCCCLXXXVIII) was a leap year starting on Sunday (click on link for calendar) of the Gregorian calendar (or a leap year starting on Tuesday of the 12-day slower Julian calendar). ...

This is a relatively young cluster that has formed directly out of the nebula. The five brightest stars in this cluster have masses on the order of 15-30 Msun, lie within a diameter of 1.5 light-years and are responsible for much of the illumination of the surrounding nebula. The Trapezium may be a sub-component of the larger Orion Nebula Cluster, a grouping of about 2,000 stars within a diameter of 20 light-years. A light-year, symbol ly, is the distance light travels in one year: exactly 9. ... A light-year, symbol ly, is the distance light travels in one year: exactly 9. ...

It is most readily identifiable by the asterism of four relatively bright, with masses on the order of The four are often identified as A, B, C, and D in order of increasing right ascension. The brightest of the four stars is C, or θ¹ C Orionis, with an apparent magnitude of 5.13. Both A and B have been identified as eclipsing binaries. Equatorial Coordinates Right ascension (abbrev. ... Theta1 C Orionis is a member of the Trapezium open cluster that lies within the Orion Nebula. ... Animation showing how an eclipsing binary stars light intensity changes as they orbit An eclipsing binary star is a binary star in which the orbit plane of the two stars lies so nearly in the line of sight of the observer that the components undergo mutual eclipses. ...

Trapezium in optical (left) and infrared light (right) from Hubble. NASA photo.

Infrared images of the Trapezium are better able to penetrate the surrounding clouds of dust, and have located many more stellar components. About half the stars within the cluster have been found to contain evaporating circumstellar disks, a likely precursor to planetary formation. In addition, brown dwarfs and low-mass runaway stars have been identified. Two views of the Trapezium cluster in the Orion Nebula, from the Hubble Space Telescope. ... Two views of the Trapezium cluster in the Orion Nebula, from the Hubble Space Telescope. ... Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble. ... The National Aeronautics and Space Administration (NASA) is an agency of the United States Government, responsible for the nations public space program. ... Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... This brown dwarf (smaller object) orbits the star Gliese 229, which is located in the constellation Lepus about 19 light years from Earth. ...

References

• E. A. Lada et al, "Circumstellar Disks in the Trapezium Cluster".
• Arcadio Poveda et al, 2005, "Low-Mass Runaway Stars from the Orion Trapezium Cluster", Astrophysical Journal, 627.

External links

• Chandra Observatory Uncovers Hot Stars In The Making, MIT Press Release, 2000.