Copyright © 2023, Columbia University Press. The Columbia Electronic Encyclopedia, 6th ed. Most of these are dwarf galaxies in Milky Way's Local Group and in orbit about one another. Of the billions of known galaxies, about 100-for example, the Andromeda Galaxy-are blue-shifted, indicating that they are approaching earth rather than receding from it. Not all celestial bodies have spectra displaced toward the red end of the spectrum. z v c Case 2: Non-Relativistic Case of Observer Moving In this case, v is much less than c. Because of the strong gravitational field, the frequency of the light emitted by atoms in a dense, compact star will be lower and the wavelengths consequently longer such effects have been observed in white dwarfs. Red shift z o s s o s 1 From the above equations, we get Red shift as follows. Red shifts are also produced by gravitation (the gravitational red shift) in accordance with the general theory of relativity. Known as the cosmological red shift, this results when the wavelength of light is stretched as it moves through the expanding universe. In the widely accepted cosmological model based on general relativity, redshift is mainly a result of the expansion of space: this means that the farther away a galaxy is from us, the more the space has expanded in the time since the light left that galaxy, so the more the light has been stretched, the more redshifted the light is, and so the. All distant galaxies show a red shift proportional to their distance from the earth as a result of the general expansion of space-time (see Hubble's law). The amount of displacement is a function of the object's recessional velocity relative to the observer. Some red shifts are the result of the Doppler effect, i.e., of the relative motion of the earth and the object away from each other. Red shift or redshift, in astronomy, the systematic displacement of individual lines in the spectrum of a celestial object toward the red, or longer wavelength, end of the visible spectrum.
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