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  2. Redshift - Wikipedia

    en.wikipedia.org/wiki/Redshift

    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

  3. Redshift survey - Wikipedia

    en.wikipedia.org/wiki/Redshift_survey

    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 ...

  4. List of common astronomy symbols - Wikipedia

    en.wikipedia.org/wiki/List_of_common_astronomy...

    This is a compilation of symbols commonly used in astronomy, particularly professional astronomy. Age (stellar) τ - age ... z - redshift; Distance description

  5. Hubble's law - Wikipedia

    en.wikipedia.org/wiki/Hubble's_law

    Redshift can be measured by determining the wavelength of a known transition, such as hydrogen α-lines for distant quasars, and finding the fractional shift compared to a stationary reference. Thus, redshift is a quantity unambiguously acquired from observation.

  6. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    In such cases, the redshift of the host galaxy allows a determination of the Hubble constant. [22] This was the case for GW170817 , which was used to make the first such measurement. [ 25 ] Even if no electromagnetic counterpart can be identified for an ensemble of signals, it is possible to use a statistical method to infer the value of H 0 ...

  7. Gravitational redshift - Wikipedia

    en.wikipedia.org/wiki/Gravitational_redshift

    In astronomy, the magnitude of a gravitational redshift is often expressed as the velocity that would create an equivalent shift through the relativistic Doppler effect. In such units, the 2 ppm sunlight redshift corresponds to a 633 m/s receding velocity, roughly of the same magnitude as convective motions in the Sun, thus complicating the ...

  8. Angular diameter distance - Wikipedia

    en.wikipedia.org/wiki/Angular_diameter_distance

    The angular size redshift relation for a Lambda cosmology, with on the vertical scale megaparsecs. The angular size redshift relation describes the relation between the angular size observed on the sky of an object of given physical size, and the object's redshift from Earth (which is related to its distance, d {\displaystyle d} , from Earth).

  9. Sloan Digital Sky Survey - Wikipedia

    en.wikipedia.org/wiki/Sloan_Digital_Sky_Survey

    The main galaxy sample has a median redshift of z = 0.1; there are redshifts for luminous red galaxies as far as z = 0.7, and for quasars as far as z = 5; and the imaging survey has been involved in the detection of quasars beyond a redshift z = 6.