What is the Speed of Galaxies by Redshift?

AI Thread Summary
To calculate the speed of galaxies based on their redshifts, the observed wavelengths of hydrogen lines are compared to the rest wavelength of 656.3 nanometers. Galaxy 1, with an observed wavelength of 659.2 nm, shows a slight redshift, indicating it is moving away at a specific speed. Galaxy 2, at 664.4 nm, exhibits a greater redshift, suggesting a faster recession speed. Galaxy 3, with an observed wavelength of 683.1 nm, has the highest redshift, corresponding to the greatest velocity away from Earth. These calculations yield speeds in km/s and as fractions of the speed of light for each galaxy.
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Homework Statement


I am trying to calculate, from their redshifts, the speed at which each of the following galaxies is moving away from us. Give your answers in both km/s and as a fraction of the speed of light.

The galaxies are:
Galaxy 1: Observed wavelength of hydrogen line is 659.2 {\rm nanometers}.
Galaxy 2: Observed wavelength of hydrogen line is 664.4 {\rm nanometers}.
Galaxy 3: Observed wavelength of hydrogen line is 683.1 {\rm nanometers}.

Additional Info:
Imagine that you have obtained spectra for several galaxies and have measured the observed wavelength of a hydrogen emission line that has a rest wavelength of 656.3 nanometers. The above galaxies are the results.
 
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oops, that should read,
"Galaxy 1: Observed wavelength of hydrogen line is 659.2 nanometers.
Galaxy 2: Observed wavelength of hydrogen line is 664.4 nanometers.
Galaxy 3: Observed wavelength of hydrogen line is 683.1 nanometers. "
 
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