Doubly ionized oxygen: Difference between revisions

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{{Short description|Oxygen ion in astronomy and atomic physics}}

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[[File:Oiii-linesp.svg|thumb|right|A [[Grotrian diagram]] of doubly ionized oxygen: forbidden transitions in the visible spectrum are shown in green.]]

'''Doubly ionized oxygen''' (also known as '''<nowiki>[O III]</nowiki>''') is a [[forbidden line]] of the [[ion]] [[oxygen|O]]²⁺. It is significant in that it emits light in the green part of the spectrum primarily at the frequency 500.7 nanometres (nm) and secondarily at 495.9 nm. Concentrated levels of <nowiki>[O III]</nowiki> are found in [[diffuse nebula|diffuse]] and [[planetary nebula|planetary]] nebulae. Consequently, narrow [[band-pass filter]]s that isolate the 501 nm and 496 nm wavelengths of light are useful in observing these objects, causing them appear at higher contrast against the filtered and consequently blacker background of space where the frequencies of <nowiki>[O III]</nowiki> are much less pronounced.

In [[astronomy]] and [[atomic physics]], '''doubly ionized oxygen''' is the [[ion]] [[oxygen|O]]²⁺ ('''O III''' in [[spectroscopic notation]]).

==Ion==

These [[emission line]]s were first discovered in the spectrums of planetary nebulae in the 1860s. At that time, they were thought to be due to a new element which was named '[[Nebulium]]'. In 1927, [[Ira Sprague Bowen]] came up with the current explanation of them being due to doubly ionized oxygen.

'''DoublyIts ionizedemission oxygen''' (also known as '''<nowiki>[O III]</nowiki>''') is aof [[forbidden line]]s ofin the [[ion]]visible [[oxygen|Ospectrum]]²⁺. Itfall isprimarily significantat inthe thatwavelength it500.7&nbsp;nm, emitsand lightsecondarily inat the495.9&nbsp;nm. greenBefore partspectra of theoxygen spectrumions primarilybecame atknown, thethese frequencylines 500.7once nanometresled (nm)to anda secondarilyspurious atidentification 495.9of nm.the substance as a new [[chemical element]]. Concentrated levels of <nowiki>[O III]</nowiki> are found in [[diffuse nebula|diffuse]] and [[planetary nebula|planetary]] nebulae]]. Consequently, narrow [[Dichroic filter|band-pass filter]]s that isolate the 501 500.7&nbsp;nm and 496 495.9&nbsp;nm wavelengths of light, that correspond to [[green]]-[[turquoise (color)|turquoise]]-[[cyan]] [[spectral colors]], are useful in observing these objects, causing them to appear at higher contrast against the filtered and consequently blacker background of space (and possibly [[light pollution|light-polluted]] terrestrial atmosphere) where the frequencies of <nowiki>[O III]</nowiki> are much less pronounced.

These [[emission line]]s were first discovered in the spectrumsspectra of [[planetary nebula|planetary nebulae]] in the 1860s. At that time, they were thought to be due to a new element which was named ''[[Nebuliumnebulium]]''. In 1927, [[Ira Sprague Bowen]] came up withpublished the current explanation ofidentifying themtheir beingsource due toas doubly ionized oxygen.<ref>{{cite journal | doi = 10.1038/120473a0 | title = The Origin of the Nebulium Spectrum | year = 1927 | author = Bowen, I. S. | journal = Nature | volume = 120 | issue = 3022 | pages = 473|bibcode = 1927Natur.120..473B | doi-access = free }}</ref>

{{science-stub}}

Other transitions include the forbidden 88.4&nbsp;μm and 51.8&nbsp;μm transitions in the far [[infrared]] region.<ref name="Osterbrock">{{cite book |last1=Osterbrock |first1=Donald E. |title=Astrophysics of gaseous nebulae and active galactic nuclei |date=1989 |publisher=University Science Books |___location=Mill Valley, Calif. |isbn=0935702229 |page=73}}</ref>

[[category:Atomic physics]]

[[category:Astronomical spectroscopy]]

Permitted lines of O III lie in the middle [[ultraviolet]] band and are hence inaccessible to terrestrial astronomy.

== See also ==

* [[H II region]]

* [[Emission nebula]]

== References ==

<references/>

{{Allotropes of oxygen}}

[[Category:Ions|O III]]

[[categoryCategory:Astronomical spectroscopy|O III]]

[[Category:Oxygen]]