Figure 5.

Magnetic (red squares) and non-magnetic (black circles) HAeBe stars on an H-R diagram. The thick blue dashed line is the birth line, the thin blue dashed lines are isochrones, the dot-dashed line is the ZAMS and the solid lines are theoretical evolutionary tracks from the birth line to the ZAMS for the masses indicated. The orange line represents a radiative/convective transition: to the left of this line, the convective envelope accounts for less than 1% of the star’s mass. A convective core appears towards the end of the PMS when the star moves downwards on the HR diagram. The open circles correspond to HD 98922 (above the birth line) and IL Cep (below the ZAMS), whose positions cannot be reproduced with the theoretical evolutionary tracks considered. From fig. 4 in Alecian et al. [40].