Recessional Velocity
The velocity at which an object moves away from an observer. The recessional velocity of a distant galaxy is proportional to its distance from Earth. Therefore, the greater the recessional velocity, the more distant the object.
where v = recessional velocity of object due to expansion of the universe, H = value of the Hubble constant at the time of observation t0, and d is the distance to the object.
where v is the recessional velocity, typically expressed in km/s. H0 is Hubble's constant and corresponds to the value of H (often termed the Hubble parameter which is a value that is time dependent) in the Friedmann equations taken at the time of ...
Hubble's Law The relationship discovered by Edwin Hubble in the 1920s that shows a linear relationship bewteen the reshift of an non-local galaxy and its recessional velocity.
31(a) shows recessional velocity plotted versus distance for the galaxies of Figure 24.30. Figure 24.31(b) is a similar plot for some more galaxies within about 1 billion pc of Earth.
where v represents the galaxy's recessional velocity, d is its distance away from Earth, and Ho is a constant of proportionality called Hubble's Constant. This equation is known as Hubble's Law.
This generalization became the basis for what is called Hubble's law, which correlates the recessional velocity of a galaxy with its distance from the Earth.
The recessional velocity of M101 is estimated to be between 330 and 450 km/s.
Discovery ...
6. Suppose an astronomer discovers a distant galaxy whose recessional velocity is 1/3 the speed of light. If the Hubble constant is 50 km/sec/Mpc how far away is the galaxy?
7. The radius of a typical neutron star is about ...
Hubble's Constant The constant of proportionality which gives the relation between recessional velocity and distance in Hubble's Law. [More Info: Photo Album] ...
Hubble's constant
A constant which defines the relation between an object's recessional velocity and its distance.
We know the material responsible for the feature towards IRAS 0857+3915 resides in that galaxy rather than ours because the redshift due to its Hubble recessional velocity has to be accounted for to get the features to line up in the figure below! ...
divided by the original wavelength; for a given relative velocity, this quantity is the same for all wavelengths or colors. For example, a red shift of 0.05 means that all wavelengths are increased by 5% because of the recessional velocity.
 See also: Velocity, Recession, Light, Distance, Telescope
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