sentences:  Pismis 24-1NE is slightly more luminous and hotter than 24-1SW, but is known to be a spectroscopic binary.This is surprising given the spectral luminosity classes, because it would make the individual supergiant stars less luminous than a single cooler giant star.It could be that the interaction between the components of 24-1NE is confusing its classification, or the O4 giant may also be a close binary.