The OB Zoo: A Digital Atlas of Peculiar Spectra

A digital atlas of 20 high‐luminosity, peculiar OB spectra in the 3800–4900 Å range is presented. The atlas is organized and discussed in terms of the following four categories: WN‐A or WNL stars, OB Iape or very late WN (WNVL) stars, iron stars, and B‐supergiant luminous blue variables (LBVs). Several objects in the earlier categories are also active or quiescent LBVs. Some (but not all) of these objects have been well studied, and extensive references are provided, as are comprehensive spectral‐line identifications. Several new morphological relationships among the objects have been recognized through this presentation. In particular, attention is drawn to the occurrence of spatial pairing between nearly identical, unusual spectra, which may have implications for a particular mode of massive‐star formation. This small sample includes one or both members of at least five such pairs. Physical explanations of these peculiar, likely transitional spectra and the relationships among them are essential for a complete understanding of massive stellar evolution.