Hertzsprung-Russell diagram. The symbols and lines largely follow Fig. 2. The standard models are connected to the best-fitting alternative models (i.e. with dust or alternative distances and reddenings) by a red line with arrow. The arrow is dashed when the alternative model has a reduced χ² that is lower by 10% or more than that of the standard model, dot-dashed when the alternative model has a reduced χ² that is larger by 10% or more, and solid otherwise. The blue line for GD-CEP-1505 indicates yet another alternative model (see text).