An Ultraviolet View of the Luminous Blue Variables

Abstract

It is, perhaps, tautological to say that the luminous blue variables (LBVs), being luminous and blue, should be ideal targets for space ultraviolet observation. In fact, many have been observed on occasion and these will be discussed in this article. Mitigating circumstances, however, conspire to make this study difficult. The LBVs are rare and tend to be apparently faint, and since they are massive and formed in the plane in our Galaxy and in active star-forming regions in other galaxies, they tend to be heavily reddened. The stars were not really studied at all in the ultraviolet until the launch of the International Ultraviolet Explorer Satellite (IUE), with the notable exceptions of photometric observations of several of the galactic stars with ANS and TD-1 and Copernicus observations of P Cygni (Hutchings et al. 1987). IUE, a small aperture (45 cm) spectrographic satellite, covering the spectral range from 1200 to 3300 A, allows for an adequate characterization of the UV properties of these stars.