The recently discovered magnetic Herbig Ae and Be stars may provide qualitatively new information about the formation and evolution of magnetic Ap and Bp stars .
We have performed a detailed investigation of one particularly interesting binary system with a Herbig Ae secondary and a late B-type primary possessing a strong , globally ordered magnetic field .
Twenty high-resolution Stokes V spectra of the system were obtained with the ESPaDOnS instrument mounted on the CFHT .
In these observations we see clear evidence for a magnetic field in the primary , but no evidence for a magnetic field in the secondary .
A detailed abundance analysis was performed for both stars , revealing strong chemical peculiarities in the primary and normal chemical abundances in the secondary .
The primary is strongly overabundant in Si , Cr , and other iron-peak elements , as well as Nd , and underabundant in He .
The primary therefore appears to be a very young Bp star .
In this context , line profile variations of the primary suggest non-uniform lateral distributions of surface abundances .
Interpreting the 0.63995 \pm 0.00009 day variation period of the Stokes I and V profiles as the rotational period of the star , we have modeled the magnetic field geometry and the surface abundance distributions of Si , Ti , Cr and Fe using Magnetic Doppler Imaging .
We derive a dipolar geometry of the surface magnetic field , with a polar strength B _ { d } = 1230 G and an obliquity \beta = 57 \degr .
The distributions Ti , Cr and Fe are all qualitatively similar , with an elongated patch of enhanced abundance situated near the positive magnetic pole .
The Si distribution is somewhat different , and its relationship to the magnetic field geometry less clear .