• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Astromony question

  • Thread starter asdf1
  • Start date
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?
 
1,349
2
what knowledge do you have?
 

Andrew Mason

Science Advisor
Homework Helper
7,521
301
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
 
734
0
How did you think of to use the Doppler effect?
 
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".
 
734
0
I see~
Thanks for correcting my spelling mistake!
 

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top