Ultraviolet Observations of Be Stars: (Review Paper)

Abstract

The history of ultraviolet studies of Be stars is barely ten years old. However, in the last decade, twelve major space experiments have observed Be stars in the ultraviolet region of the spectrum, and ultraviolet data for over 30 Be stars are now available in the literature. Table I shows some of the characteristics of the experiments. They include two rockets, five astronomical satellites, three manned satellites, and one planetary probe. Except for the rocket experiments, they are primarily survey instruments, which have provided ultraviolet data on early-type stars in general, and these data have proved to be extremely useful as standards of comparison for Be stars. Of the twelve spacecraft, two are presently operating: Copernicus and ANS. The two experiments complement one another very nicely in that the ANS experiment can obtain absolute continuous flux distributions, while the Princeton experiment can obtain high-resolution line spectra for the brighter Be stars.