On the Alignment of T Tauri Stars with the Local Magnetic Field

Abstract

Magnetic field is believed to play an important role in the collapse of a molecular cloud. In particular, due to the properties of magnetic forces, collapse should be easier along magnetic field lines, as supported by the large-scale sheet-like structure of the Taurus giant molecular cloud for instance. Here we investigate whether such a prefered orientation for collapse is present at a much smaller scale, that of individual objects. We use recent high-angular resolution images of T Tauri stars located in the Taurus star-forming region to find the orientation of the symmetry axis of each star+jet+disk system and compare it to that of the local magnetic field. We find that i) the orientations of the symmetry axis of T Tauri stars are not random with respect to the magnetic field, and ii) that young stars that are associated to a jet or an outflow are oriented very di erently from those which do not have a detected outflow. We present some implications of this puzzling new result.