Question

If you find that the hydrogen alpha line in a star’s spectrum occurs at a wavelength of 656.45 nm, what is the star’s approximate radial velocity? Note that the rest wavelength of this line is 656.30 nm.

Answer 1

The answer to the question is

The star’s approximate radial velocity is 68.52 km/s

Step-by-step explanation:

To solve the

The formula is

`(\lambda-\lambda_(rw))/(\lambda_(rw)) = (v_r)/(c)` where

`v_r` = velocity of the star

λ = Star's spectrum wavelength = 656.45 nm

`\lambda_(rw)` = Rest wavelength = 656.30 nm

c = Speed of light = 299 792 458 m / s

Therefore we have

`(656.45-656.30)/(656.30) =(v_r)/(299 792 458)` or
`v_r` = 68518.7699 m/s or 68.52 km/s