Doubly ionized oxygen
Encyclopedia
Doubly ionized oxygen is a forbidden line of the ion
O
2+. It is significant in that it emits light in the green part of the spectrum primarily at the wavelength 500.7 nanometres (nm) and secondarily at 495.9 nm. Concentrated levels of[O III] are found in diffuse and 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 to appear at higher contrast against the filtered and consequently blacker background of space (and possibly light polluted terrestrial atmosphere) where the frequencies of[O III] are much less pronounced.
These emission lines 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.
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
2+. It is significant in that it emits light in the green part of the spectrum primarily at the wavelength 500.7 nanometres (nm) and secondarily at 495.9 nm. Concentrated levels of
Planetary nebula
A planetary nebula is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life...
nebulae. Consequently, narrow band-pass filter
Dichroic filter
A dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the color of light that they...
s that isolate the 501 nm and 496 nm wavelengths of light 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 polluted terrestrial atmosphere) where the frequencies of
These emission lines 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
Nebulium
Nebulium was a proposed element found in a nebula by William Huggins in 1864. The strong green emission lines of the Cat's Eye Nebula, discovered using spectroscopy, led to the postulation that an as yet unknown element was responsible for this emission...
. In 1927, Ira Sprague Bowen
Ira Sprague Bowen
Ira Sprague Bowen was an American astronomer. In 1927 he discovered that nebulium was not really a chemical element but instead doubly ionized oxygen.-Life and work:...
came up with the current explanation of them being due to doubly ionized oxygen.