Polarimetry of the young Herbig Ae star HD 139614 Differences of polarimetric behaviour of Vega-type stars

We present optical polarimetric data of the Herbig Ae star HD 139614 and discuss its behaviour relative to similar stars. In spite of a low level of polarization ( 0.05-0.2%), polarimetric variability on a time-scale of days was detected during a four night synoptic study. The difference in the level of the polarization for HD 139614 relative to other Herbig Ae/Be stars such as HD 141569, HD 142666 and HD 169142 might be due to the inclinations and viewing aspects of their circumstellar disks and to their different evolutionary stages. This hypothesis is consistent with the photometric behaviour of these stars, their v sin i values and spectral energy distribution in the near and far IR.