Doubly ionized oxygen: Difference between revisions

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'''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 5007 [[Ångström]]s and secondarily at 4959 Ångströms. 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 501nm and 496nm 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.

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]]'. AfterIn more than 50 years1927, [[Ira Sprague Bowen]] came up with the current explanation of them being due to doubly ionized oxygen.

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