Disk Orientations in PMS Binary Systems Determined Through Polarimetric Imaging with UT1/FORS

Abstract

Photons are an expensive product of astronomical telescopes. The wide wavelength and instrumental techniques coverage offered by the VLT allows astronomers to dissect the incident radiation in many ways: spectroscopy and imagery are well-known observing techniques to VLT observers. A maybe less well-known technique is polarimetry. The IPOL mode of FORS on UT1 allows to measure high-quality polarimetric images on a wide field of view. We used this instrument during period 65 to determine the respective orientation of circumstellar disks in pre- Main-Sequence binaries. In this paper, we present our method and first results obtained with FORS/IPOL. Thanks to the top-quality assistance of the VLT and FORS teams, our run was remarkably successful and the instrument appears extremely well adapted to fine polarimetric measurements on large fields of view. Our first results suggest that circumstellar disks tend to be aligned in PMS binaries.