Doubly ionized oxygen
In astronomy and atomic physics, doubly ionized oxygen is the ion O2+ (O III in spectroscopic notation).
Ion
[edit]Its emission of forbidden lines in the visible spectrum fall primarily at the wavelength 500.7 nm, and secondarily at 495.9 nm. Concentrated levels of O III are found in emission and planetary nebulae. Consequently, narrow band-pass filters that isolate the 500.7 nm and 495.9 nm wavelengths of light, that correspond to green-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-polluted terrestrial atmosphere) where the frequencies of [O III] are much less pronounced.
These emission lines were first discovered in the spectra of planetary nebulae in the 1860s. At that time, they were thought to be due to a new chemical element which was named nebulium. In 1927, Ira Sprague Bowen published the current explanation identifying their source as doubly ionized oxygen.[1]
Other transitions include the forbidden 88.4 μm and 51.8 μm transitions in the far infrared region.[2]
Permitted lines of O III lie in the middle ultraviolet band and are hence inaccessible to terrestrial astronomy.
See also
[edit]References
[edit]- ^ Bowen, I. S. (1927). "The Origin of the Nebulium Spectrum". Nature. 120 (3022): 473. Bibcode:1927Natur.120..473B. doi:10.1038/120473a0.
- ^ Osterbrock, Donald E. (1989). Astrophysics of gaseous nebulae and active galactic nuclei. Mill Valley, Calif.: University Science Books. p. 73. ISBN 0935702229.