You observe a spectral line of hydrogen at a wavelength of 522.5 nm in a distant galaxy. the rest wavelength of this line (known as hβ or hydrogen beta) is 486.1 nm. what is the radial velocity of this galaxy in kilometers per second? is it moving toward or away from earth?

Solved

Explanation:

due to Doppler effect on light

v- radiation velocity of approach

c= velocity of light

λ=522.5 nm  wavelength from the distant star

λ_0 = 486.1 rest wavelength

putting these values to find v

=0.0748817*3*10^8

=1.92×10^8 m/ses

=1.92×10^5 Km/sec

since the sign of velocity is negative it is moving away from the Earth.

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