Stellar Evolution up to the Final Stages

Abstract

The nature of the observed stars has been a subject of discussion and speculation since the early days of civilization. Atomists Leucippus and Democritus thought that the Milky Way was made of stars, which they considered too small to be distinguished from one another. By the time of the Indian mathematician Aryabhata (5th century A.D.), there existed in the East the notion that stars were, in fact, other suns. It would have been immediately obvious that they would have to be at enormous distances for this hypothesis to make sense. Other important speculations were formulated in the West. For example, in Giordano Bruno’s writings, not only were the stars identified as distant suns, but inhabited planetary systems accompanied them, putting the author on a direct collision course with the Roman Catholic Church. What is certain is that it was only in the early 19th century, with the works of W. Herschel and J. von Fraunhofer, that the star = Sun identification was shown to be correct: the absorption lines of several nearby stars were observed, revealing their kinship with the lines observed in the solar spectrum. This Chapter addesses the construction of stellar models and the important featurese of Stellar Evolution till the final stages leading to explosions/compact object formation.