There is no need to convert nanometres to metres as units cancel top and bottom. Wei & Wu 2017, Chen, Kumar & Ratra 2017, Verde et al. Under the assumption of CDM, H (z) H 0 sqrt ( m (1+z) 3 + + k (1+z) 2) (e.g. So if a distant galaxy emits a characteristic spectral line of 91 nm ( ultraviolet light at the 'Lyman limit') but when observed on Earth it appears to be 640 nm (red) we can calculate the red shift using this equation: The time-dependent expansion of spacetime is characterized in the FLRW equations as a function of redshift z by the Hubble parameter H (z). The following equation is used to calculate redshift: to get the age of the universe at z 10 you would therefore have to divide the age now, by the factor 36.5. the oversimplified formula says the scale factor R (t) is proportional to the age (2/3) so clearly 11 age ratio (2/3) so age ratio 11 (3/2) 36.5. This is because galaxies are receding (moving away) at such high speeds that relativistic effects need to be considered in calculations. z 10 means a ratio of 11 in the scale factor. The Doppler equation used for sound calculations cannot be used in this situation. Redshift is also the name of the factor z indicating the relative change in wavelength due to the Doppler shift for a receding galaxy. The upper diagram shows the absorption spectrum from a stationary galaxy with one wavelength of light and no redshift. Lower diagram shows spectrum of light redshifted from a distant galaxy moving away from the Earth This indicated the stars were moving away from Earth (just as the sound of a siren moving away from you has a decreased frequency and increased wavelength).Īs the light was shifted towards the red end of the spectrum (lower frequency/longer wavelength) this phenomenon was termed 'redshift'. For question one my Redshift is z0.0029 My second question is z-0.0020what is both velocities using the equation This problem has been solved Youll get a. The same shifts in frequency and wavelength are also observed for light coming from stars in distant galaxies.īy comparing the light from distant stars with the spectrum of light from our Sun it was noticed that the spectra from distant stars had a slightly decreased frequency and slightly increased wavelength.
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