An absorption line is noted at 655nm in the spectrum of the star.The same absorption line is found at 642nm...

Question

1) The spectrum of a certain star is measured. An absorption line is noted at 655nm in the spectrum of the star.The same absorption line is found at 642nm in a spectrum measured in a laboratory. Is the star moving towards or away from the Earth? What is the velocity of the stars motion towards or away from the Earth?

2) The spectrum of a certain star is measured. An absorption line is noted at 456nm in the spectrum of the star.The same absorption line is found at 468nm in a spectrum measured in a laboratory. Is the star moving towards or away from the Earth? What is the velocity of the stars motion towards or away from the Earth?


So, if the numbers grow does it mean that it is moving away from the Earth? Also, is there a good formula to figure these kind of questions out? Thank you for your help!!!

Answer 1

If moving toward the red spectrum, then moving away. If toward the blue, then closer.

Answer 2

particular. The lines on the emission spectra correspond to the gaps on the absorption spectra. they do no longer all could be latest whether, counting on the excited state of the element or potential that the element is absorbing respectively. bye for now.