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The redshift observed in astronomy can be measured because the emission and absorption spectra for atoms are distinctive and well known, calibrated from spectroscopic experiments in laboratories on Earth. When the redshift of various absorption and emission lines from a single astronomical object is measured, z is found
Gravitational redshift can be interpreted as a consequence of the equivalence principle (that gravitational effects are locally equivalent to inertial effects and the redshift is caused by the Doppler effect) [5] or as a consequence of the mass–energy equivalence and conservation of energy ('falling' photons gain energy), [6] [7] though there ...
Redshift quantization, also referred to as redshift periodicity, [1] redshift discretization, [2] preferred redshifts [3] and redshift-magnitude bands, [4] [5] is the hypothesis that the redshifts of cosmologically distant objects (in particular galaxies and quasars) tend to cluster around multiples of some particular value.
In astronomy, a redshift survey is a survey of a section of the sky to measure the redshift of astronomical objects: usually galaxies, but sometimes other objects such as galaxy clusters or quasars. Using Hubble's law, the redshift can be used to estimate the distance of an object from Earth. By combining redshift with angular position data, a ...
[36] [37] The first accurate measurement of the gravitational redshift of a white dwarf was done by Popper in 1954, measuring a 21 km/s gravitational redshift of 40 Eridani B. [37] The redshift of Sirius B was finally measured by Greenstein et al. in 1971, obtaining the value for the gravitational redshift of 89 ± 16 km/s , with more accurate ...
Distances to astronomical objects may be determined through parallax measurements, use of standard references such as cepheid variables or Type Ia supernovas, or redshift measurement. Spectroscopic redshift measurement is preferred, while photometric redshift measurement is also used to identify candidate high redshift sources.
Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe.They are often used to tie some observable quantity (such as the luminosity of a distant quasar, the redshift of a distant galaxy, or the angular size of the acoustic peaks in the cosmic microwave background (CMB) power spectrum) to another quantity that is ...
The Center for Astrophysics (CfA) Redshift Survey was the first attempt to map the large-scale structure of the universe.. The first survey began in 1977 with the objective of calculating the velocities of the brighter galaxies in the nearby universe by measuring their redshifts at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.