Mon, 08/01/2022 - 17:49
Hi All,
I was just thinking about spectroscopy and red shift due to stars rotation and other factors. Why is this not an issue with photometry in our common photometric passbands? Would it not affect magnitude measurements?
Because the red shift is VERY small and the passbands on filters is very wide.
Peter
ok...i figured that must be the case...makes sense now duh...thank you peter :)
Redshift from Doppler shift
λ(redshifted) = [(1+v/c)÷(1-v/c)]^0.5)×λ(at rest)
So what would be the redshift of let say the Parker Solar Probe if it was moving away from us at its top speed of 119 miles per second
v/c = 119/186282 = 0.00064 times the speed of light
Plug it in with a wavelength roughly in the middle of the visible spectrum of 5500 Angstroms for the wavelength emitted from something at rest relative to the observer
λ(redshifted) = [(1+0.00064)÷(1-0.00064)]^0.5)×5500 Angstroms
λ(redshifted) = 5503.7 Angstroms
Not much of a shift in wavelength even at that speed.