A statistical investigation has been made of rotation and macro turbulence in early-type Ia and lab supergiants. The study has had two principal objectives: first, to see whether it is possible to separate the contributions to the observed line broadening arising from these two forms of macroscopic motion; second, if possible, to use the recovered rotational component to determine whether significant amounts of angular momentum have been lost during evolution away from the main sequence. The principal results are: (1) At all spectral types in the range BO-AS both rotation and macroturbulence contribute to the observed line broadening. In the early B stars, rotation is as important a broadening agent as largescale mass motion. In the middle-B and A stars turbulence dominates, but there still is an appreciable contribution from rotation. (2) In spite of the fact that the stars observed seem to be losing mass, there is no strong evidence for significant loss of angular momentum.
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Jeffrey D. Rosendhal (1970) studied this question.