  Models of magnetically driven accretion and outflows reproduce many
observational properties of T Tauri stars, but the picture is much less clear
for the Herbig Ae/Be stars, due to the poor knowledge of their magnetic field
strength and topology. The Herbig Ae star PDS2 was previously included in two
magnetic studies based on low-resolution spectropolarimetric observations. Only
in one of these studies the presence of a weak mean longitudinal magnetic field
was reported. In the present study, for the first time, high-resolution HARPS
spectropolarimetric observations of PDS2 are used to investigate the presence
of a magnetic field. A firm detection of a weak longitudinal magnetic field is
achieved using the multi-line singular value decomposition method for Stokes
profile reconstruction (<B_z>=33+-5G). To gain better knowledge of typical
magnetic field strengths in late Herbig Be and Herbig Ae stars, we compiled
previous magnetic field measurements, revealing that only very few stars have
fields stronger than 200G, and half of the sample possesses fields of about
100G and less. These results challenge our current understanding of the
magnetospheric accretion in intermediate-mass pre-main sequence stars as they
indicate that the magnetic fields in Herbig Ae/Be stars are by far weaker than
those measured in T Tauri stars.
