Evolution and Hydrodynamics of Rotating Stars

Abstract

Stellar evolution sequences of models of spherical stars were very successful in the late 1950’s and early 1960’s in outlining the major stages and even many of the details of the stellar life cycle. Since then, we have continued to modify the physics and model properties to explain discrepancies as new observations became available. For the most part this has been successful, but there remain some pieces of the puzzle which either do not fit or must be tortured into place. One might divide these into three particular classes - surface abundances of elements show peculiarities for which traditional stellar evolution does not easily account, observed global properties such as the masses of massive main sequence stars do not agree with stellar evolution calculations, and regions of the H-R diagram are not populated either at all or to the extent that observations indicate (such as the number ratio of blue to red supergiants, the region between the end of core hydrogen burning and the beginning of core helium burning in massive stars, and the location of blue loops for some intermediate mass stars).