The Redshift: star HD 94028 in stellar motion


HD94028: Red shift of a star

This is the stellar motion of the star, HD-94028, in space. The light emitted by the star is collected through a diffraction grating to split it up into its various components, before being analysed.

When the intensity of the hydrogen-alpha radiation plotted against the wavelength, the above graph could be obtained.

Under normal circumstances, the wavelength of the hydrogen-alpha radiation is 656.28 nm. The measured wavelength of the same, however, appears to be 656.62 nm, clearly indicating an increase in wavelength that in turn shows the radiation line being shifted towards the red end of the spectrum; the greater the wavelength, the closer the radiation to red.

This is the phenomenon of redshift: the stars – and galaxies – are moving away from the Earth; the speed is very significant too, as the following calculations indicate:

From the graph, redshift factor = 656.62 – 656.28 nm

Speed = redshift factor x 2.9978 x 100000 = 151.3139 km/s

This is called the speed of receding of the star in question.


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