The extension of OB star winds to lower luminosities

Mass loss rates derived for a number of early-to-mid B main-sequence stars have been compared with extrapolations of recently derived empirical correlations between M and stellar parameters for luminous OB stars. Although there is sufficient scatter within the sample of B star mass loss rates to obscure any correlations that may exist within this group, the order of magnitude of the rates for these stars is consistent with a simple dependence on luminosity over the range from Of to mid-B, and is not consistent with previously derived correlations involving a dependence on mass or radius. This implies that luminosity is the dominant factor in driving the mass loss through the range of spectral types from mid-B main sequence to Of. It appears that the winds in Be stars may represent a straightforward extension of the OB star wind phenomenon to lower luminosities, although the internal scatter allows the possibility that factors other than L may have some influence on M for the B main-sequence stars. There appears to be no significant difference between B and Be stars in terms of their wind characteristics.