Magnetic (red squares) and non-magnetic (black points) Herbig Ae/Be stars plotted in a Hertzsprung-Russell diagram. The red square with error bars corresponds to HD 190 073. The CESAM pre-MS evolutionary tracks for 1.5, 2, 3, 4, and 6 M_⊙ (black full lines), 0.01, 0.1, 1 and 10 Myr isochrones (blue thin dashed lines), and the zero-age main-sequence (black dot-dashed line) are also plotted. The birthline taken from Behrend & Maeder (2001) is plotted with a blue thick dashed line. The limit over which the convective envelope is smaller than 1% of the stellar mass, and the CC-birthline (see text) are overplotted with orange dot-dot-dot-dashed lines.