Elena Redaelli
Max Planck Institute for Extraterrestrial Physics
Polarimetry with SOFIA: the interplay between magnetic fields and kinematics in low-mass cores
Magnetic fields are believed to play a crucial role on the evolution of molecular clouds and cores. While dense structures such as filaments are thought to be formed from magnetically driven cloud contraction, at core scales the magnetic field can be a strong source of support against the gravitational collapse. Most polarimetric observations are sensitive either to large, cloud scales or to smaller core scales, but there are not many observations reported on the cloud-core transition phase (0.1-1.0 pc). Single-dish observations are thus of great importance to understand the role of magnetic fields on the formation of cores. We have used the SOFIA/HAWC+ camera to perform polarimetric observations at of the source IRAS15398 in the Lupus I cloud, a highly magnetised filamentary cloud. Our results show an ordered magnetic field aligned with the large-scale cloud field and with the direction of the bipolar outflow. Using the angular dispersion function analysis, we estimate a magnetic field strength of B= 78 µG, which is expected to be accurate within a factor of two. The measured mass-to-flux parameter is λ = 0.95, indicating that the core is in a transcritical regime. In subsequent work, we use APEX observations of molecular tracers to investigate the kinematic properties of the source. We report a possible accretion flow from the filament toward the central object, seen as a velocity gradient in DCO+ emission. Towards the protostar, the velocity field is consistent with core rotation, and the magnetic field appears aligned with the rotation axis.
