Jharkhand PSC Prelim Exam 2006 Solved Paper

(4) The colour of the stars reflects the age of the stars.
Now red indicated that the star is aged. Colour is reflected from the fusion reaction it indicated the temperature. If the temperature is high then the star is young. The star will be blue during young stage which indicates high temperature and the nuclear fusion reaction is going on very fast.
if it is aged the colour intensity will decline till red which shows low temperature due to less fusion reaction.