Posted by **Mark** on Monday, November 16, 2009 at 11:01am.

A high-velocity star HVS 1 is moving at 600 km/s, 0.2% speed of light. Assuming the HVS 1 is moving away from us, and that its velocity is oriented entirely along our line of sight, determine the Doppler shift of the Ha spectral line (6562.8 Angstrom) produced by this star. Is the spectral line located to the red or to the blue of its rest wavelength? Any help would be appreciated. Thanks.

- Physics-Astronomy -
**drwls**, Monday, November 16, 2009 at 11:47am
If the star moving away from earth, which is the usual case, the shift is towards the red.

You can use the formula

(delta lambda)/lambda = v/c = 0.002

'delta lambda' is the Doppler shift of wavelength, lambda. That is what they are asking for.

There is a more accurate relativistically correct formula that is the same whether the observer or the source is moving, but at this low v/c value, it gives nearly the same result.

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