Astromony question

  • Thread starter asdf1
  • Start date
  • #1
734
0
There's an astromony question that I'm stuck on~
" A distant galaxy in the constellation Hydra is receding from the earth at 6.12*10^7 m/s. By how much is a green spectral line of wavelength 500nm (1nm=10^(-9) )emitted by this galaxy shifted toward the red end of the spectrum?
 

Answers and Replies

  • #2
1,356
2
what knowledge do you have?
 
  • #3
Andrew Mason
Science Advisor
Homework Helper
7,620
362
asdf1 said:
There's an astromony question that I'm stuck on~
" A distant galaxy in the constellation Hydra is receding from the earth at 6.12*10^7 m/s. By how much is a green spectral line of wavelength 500nm (1nm=10^(-9) )emitted by this galaxy shifted toward the red end of the spectrum?
Just use the relativistic doppler effect:

[tex]\nu_{obs}/\nu_{source} = \sqrt{\frac{1+\beta}{1-\beta}}[/tex]

where [itex]\beta = v/c = .204[/itex] and [itex]\nu_{source} = c/\lambda_{source}[/itex]

AM
 
  • #4
734
0
How did you think of to use the Doppler effect?
 
  • #5
551
1
Probably because the question is about the Doppler effect (well, it's about red shift, which is to do with the Doppler effect). Also, you mean "astronomy", not "astromony".
 
  • #6
734
0
I see~
Thanks for correcting my spelling mistake!
 
Top