In this paper we report the results of high-resolution circular spectropolarimetric monitoring of the Herbig Ae star V380 Ori , in which we discovered a magnetic field in 2005 .
A careful study of the intensity spectrum reveals the presence of a cool spectroscopic companion .
By modelling the binary spectrum we infer the effective temperature of both stars : 10500 \pm 500 K for the primary , and 5500 \pm 500 K for the secondary , and we argue that the high metallicity ( [ M / H ] = 0.5 ) , required to fit the lines may imply that the primary is a chemically peculiar star .
We observe that the radial velocity of the secondary ’ s lines varies with time , while that of the the primary does not .
By fitting these variations we derive the orbital parameters of the system .
We find an orbital period of 104 \pm 5 d , and a mass ratio ( M _ { P } / M _ { S } ) larger than 2.9 .
The intensity spectrum is heavily contaminated with strong , broad and variable emission .
A simple analysis of these lines reveals that a disk might surround the binary , and that a wind occurs in the environment of the system .
Finally , we performed a magnetic analysis using the Least-Squares Deconvolved ( LSD ) profiles of the Stokes V spectra of both stars , and adopting the oblique rotator model .
From rotational modulation of the primary ’ s Stokes V signatures , we infer its rotation period P = 4.31276 \pm 0.00042 d , and find that it hosts a centred dipole magnetic field of polar strength 2.12 \pm 0.15 kG , with a magnetic obliquity \beta = 66 \pm 5 ^ { \circ } , and a rotation axis inclination i = 32 \pm 5 ^ { \circ } .
However , no magnetic field is detected in the secondary , and if it hosts a dipolar magnetic field , its strength must be below about 500 G , to be consistent with our observations .