Question

. Hydrogen has an absorption line at a wavelength λ0 = 656.3 nm (as long as the hydrogen is at rest). You observe a distant galaxy for which the same hydrogen absorption line has a wavelength λ = 715.4 nm. (i) What is the redshift, z = (λ − λ0)/λ0, of the galaxy? (ii) What is the radial velocity of the galaxy, in kilometers per second? (iii) From Hubble’s law, what is the distance to the galaxy?

[Hint: assume H0 ≈ 71 km/s/Mpc.]

Answer #1

the final answer is the approximate answer. It may vary in a small value

Suppose that you have obtained spectra of several galaxies and
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wavelength = 656.3nm) to be:
Galaxy 1: 659.4 nm.
Galaxy 2: 664.1 nm. Galaxy 3: 675.7 nm.
10. [4pt] Calculate the redshift, z, for each of these
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11. [4pt] Calculate the radial velocity of each of these
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