Peculiar velocity

Peculiar velocity

In physical cosmology, the term peculiar velocity refers to the components of a receding galaxy's velocity that cannot be explained by Hubble's law.

According to Hubble, and as verified by many astronomers, a galaxy is receding from us at a speed proportional to its distance. The relationship between speed and distance would be exact in the absence of other effects.

Galaxies are not distributed evenly throughout observable space, but typically found in groups or clusters, ranging in size from fewer than a dozen to several thousands. All these nearby galaxies have a gravitational effect, to the extent that the original galaxy can have a velocity of over 1,000 km/s in an apparently random direction. This velocity will therefore add, or subtract, from the radial velocity that one would expect from Hubble's law.

The main consequence is that, in determining the distance of a single galaxy, a possible error must be assumed. This error becomes smaller, relative to the total speed, as the distance increases.

A more accurate estimate can be done by taking the average velocity of a group of galaxies: the peculiar velocities, assumed to be essentially random, will cancel each other, leaving a much more accurate measurement.


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • peculiar velocity — noun velocity with respect to the local standard of rest • Hypernyms: ↑speed, ↑velocity …   Useful english dictionary

  • Peculiar star — In astrophysics, peculiar stars have distinctly unusual metal abundances, at least in their surface layers. Chemically peculiar stars (CP stars) are common among hot main sequence (hydrogen burning) stars. These hot peculiar stars have been… …   Wikipedia

  • peculiar motion — noun : the actual motion of a star after its observed proper motion and radial velocity are corrected for the effect of the sun s motion * * * peculiar motion see ↑proper motion under ↑proper • • • Main Entry: ↑peculiar …   Useful english dictionary

  • Atlas of Peculiar Galaxies — The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies produced by Halton Arp. A total of 338 galaxies are presented in the atlas, which was originally published in 1966 by the California Institute of Technology.The primary goal of the… …   Wikipedia

  • escape velocity — es*cape vel*o ci*ty, n. (Physics) The minimum velocity at which an object must be moving in order for it to overcome the gravitational attraction of a massive celestial body, such as the earth or the sun, and escape beyond its gravitational field …   The Collaborative International Dictionary of English

  • cosmos — /koz meuhs, mohs/, n., pl. cosmos, cosmoses for 2, 4. 1. the world or universe regarded as an orderly, harmonious system. 2. a complete, orderly, harmonious system. 3. order; harmony. 4. any composite plant of the genus Cosmos, of tropical… …   Universalium

  • Comoving distance — Physical cosmology Universe · Big Bang …   Wikipedia

  • Dark flow — Physical cosmology Universe · Big Bang …   Wikipedia

  • Gliese 1 — GJ 1 Observation data Epoch J2000      Equinox J2000 Constellation Sculptor Right ascension 00h 05m 24.4279s[1] …   Wikipedia

  • Big Bang — This article is about the cosmological model. For the sitcom, see The Big Bang Theory. For other uses, see Big Bang (disambiguation) …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”