Answer Happy

[98] Astronomers have found that light from distant stars in other galaxies are redshifted by relative motion (doppler shift) by the relative motion of galaxies. Assuming the light produced by a star is sent at a wavelength of 550 nm, how fast must the distant star be traveling if its light reaches us at a wavelength of 3.33 um? Astronomers use a value called "z" to measure the redshifting where (assuming the star is just moving away from us radially) z = -obs --Aemit what is the z of this star? Note: This is Doppler redshifting, but there is also gravitational redshifting and this has a much larger effect in the end. damit