Orion nebula
The Orion Nebula (also known as Messier 42), is the brightest star forming, diffuse nebula in the sky, situated south of the belt of Orion. Having an apparent magnitude of 3, the nebula can be seen by the unaided eye in moderately dark skies. It is estimated to be some 24 light years across and is some 1,344±20 light years from Earth[1]. The Orion Nebula itself is only part of a vastly larger star forming nebular region called the Orion Molecular Cloud Complex.
History
The Orion Nebula is one of the most studied and photographed objects in the night sky, and is among the most intensely studied celestial features by astronomers that have revealed a wealth of knowledge on how stars and planetary systems are formed from collapsing clouds of gas and dust.
The nebula was probably known to ancient people as it is visible to the naked eye, the Maya had a folk tale which dealt with the region of the sky with Orion[2]. Ptolemy did include it in the Almagest (Great Book), Tycho Brahe also made note of the object in the late 16th century, but neither seemed to recognize it as a nebula.
Credit for discovering the nebula is given to Nicholas-Claude Fabri de Peiresc who in 1610 first recorded of a cloudy nebulosity in the Orion constellation. Jesuit astronomer Johann Baptist Cysatus independently found the nebula in 1611 and published a note about it seven years later[3]. It was independently rediscovered by Christiaan Huygens in 1656, who is often created for it's discovery. The designation M42 was given to the nebula by Charles Messier, who recorded it in the first edition of his catalog of deep sky objects in 1774 (completed in 1771)[3]. The nebula is also known as the first deep sky observation by William Herschel with his new self-constructed reflecting telescope in 1774[3].
The gaseous nature of the Orion Nebula was identified in 1865 by William Huggins with the help of spectroscopy. On September 30, 1880, the Orion Nebula became the first nebula to have a successful photograph taken by it, by Henry Draper, who later obtained a second more detailed photograph of the Orion Nebula. In 1993 In 1993, the Hubble Space Telescope first looked to the Orion Nebula, and in 2005 recorded the most detailed imagery of the nebula yet, photographing over 3,000 stars contained within[4].
Nebula Structure
Various features in the Orion Nebula have been given their own names by observers over the years. The dark lane that extends from the north toward the bright region is called the "Fish's Mouth", it is here where a cluster of newborn stars are found called the Trapezium Cluster. The illuminated regions to both sides are known as the "Wings". Other features include "The Sword", "The Thrust" and "The Sail".
The Orion Nebula is the primary example of a stellar nursery where new stars are being born. Recent observations of the nebula have revealed approximately 700 stars in various stages of formation within the nebula. In addition the Hubble have found over 150 proplys, or protoplanetary disks in the nebula[5]. Such systems are considered to be the earliest stages of solar system formation. The large number located just in this one nebula is viewed as evidence that the formation of star systems is a common occurrence in the universe.
References
- ↑ http://arxiv.org/abs/0902.3913
- ↑ http://pqasb.pqarchiver.com/skyandtelescope/access/886319051.html?dids=886319051:886319051&FMT=CITE&FMTS=CITE:PAGE&date=Feb+1999&author=E+C+Krupp&desc=Igniting+the+Hearth
- ↑ 3.0 3.1 3.2 http://messier.obspm.fr/Mdes/dm042.html
- ↑ http://adsabs.harvard.edu/abs/2005AAS...20714601R
- ↑ http://adsabs.harvard.edu/abs/1996AJ....111.1977M
