Dusty Blue Supergiants: News from High-Angular Resolution Observations
Figure 1
WISE mid-IR colour-colour diagram for galactic BSGs. The full lines are the colours produced by the simple addition of two blackbodies representing the star (of 20 000 K) and the dust (with a variety of temperatures as indicated) for a constant of 0.6%. The sgB[e] candidates (blue triangles [9]) and regular BSGs (blue dots) are indicated from the sample studied by Crowther et al. [20]. The colours for stars with excess bf-ff emission were determined empirically. Green triangles are Cyg variables, namely, HD 64760, HD 163899, HD 46769, HD 152249, and HD 199478.
