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From Wikipedia, the free encyclopedia
The Strömgren photometric system, abbreviated also as uvbyβ or simply uvby, and sometimes referred as Strömgren - Crawford photometric system, is a four-colour medium-passband photometric system plus Hβ (H-beta) filters for determining magnitudes and obtaining spectral classification of stars. Its use was pioneered by the Danish astronomer Bengt Strömgren in 1956[1] and was extended by his colleague the American astronomer David L. Crawford in 1958.[2]
It is often considered to be a powerful tool and successful investigating the brightness and effective temperature of stars. This photometric system also has a general advantage as it can be used to measure the effects of reddening and interstellar extinction.[3] This system also allows calculation of parameters from the and filters without the effects of reddening, termed and .[3]
The following table shows the characteristics of each of the filters used (represented colors are only approximate):
u | v | b | y | βnarrow | βwide | |
---|---|---|---|---|---|---|
Peak wavelength (nm) | 350 | 411 | 467 | 547 | 485.8 | 485 |
Half-width (nm) | 30 | 19 | 18 | 23 | 2.9 | 12.9 |
There are four main highly applied and technical indices: ; ; ; and .
Where;
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