Astrophysics (Index)About

Butcher-Oemler effect

(observation of more blue galaxies at z > 0.3)

The Butcher-Oemler effect (sometimes abbreviated BOE) is an observed distribution of the characteristics galaxies, that at middle-to-high redshifts (z = 0.3 up to perhaps z = 1), there is a higher percentage of blue galaxies than found nearer the present time. Blue indicates spectral class stars which are a sign of very recent star formation, so the observed distribution suggests a higher star formation rate in that era than at present. The effect was published in 1978 and is still of research interest.

(galaxies,cosmology,star formation)
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