Star Surface Temperature

2. How is the colour related to surface temperature of the star?
The correlation between the surface temperature of a star and its colour is due to the phenomena known as black body radiation .A star is a black body,where it aborbs all the radiation falling upon it.AS its temperatures gets hotter thanits surrounding,the star radiates its on electromagnetic radiation,known as black body radiation. This radiation is distributed unevenly but contionously through multiple wavelengths of the electromagnetic spectrum and is dependent on the temperature of the black body. As is evident from the graph. Evident on this graph is that as the peaks increases,the peaks move towards the shorter wavelengths ,whilst at the lower temperatures ,the radiation lies in the non-visible infra-red. This relationship is summerised in Wiens law :λmaxT=W where max wavelength times temperature equals a constant .Using a spectrophotometer to measures the wavelength of maxium output ,temperature can be accurately calculated using Wiens law.