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# You obtain spectra for two galaxies and measure the observed wavelength of a hydrogen emission line...

You obtain spectra for two galaxies and measure the observed wavelength of a hydrogen emission line that has a rest wavelength of 656.3 nm. Here are your results: Galaxy 1: Observed wavelength of hydrogen line is 672.9 nm Galaxy 2: Observed wavelength of hydrogen line is 692.6 nm

(a) Calculate the redshift, z, for each of the two galaxies.

(b) What is each one’s recessional velocity (in km/s)?

(c) Which of these galaxies is farther away from you?

(d) How many times farther away is it?

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