IA/U.Lisboa Seminar - On magnetic fields and what we can learn from polarimetry in protoplanetary disks - 25 julho 2017

Magnetic fields are predicted to be an important factor for a wide range of physical processes in protoplanetary disks. In the classical picture, (sub-)mm continuum polarisation is the tracer for magnetic fields in disks. Aspherical dust grains, whose thermal emission is intrinsically polarized, get aligned by the magnetic field due to radiative torques. In recent years, however, this picture has been challenged. New theoretical studies show that (sub-)mm continuum polarisation can also be created by scattering of the thermal dust emission or arise from aspherical grains which are aligned by the radiation field rather than the magnetic field. These three mechanisms trace fundamentally different physics in protoplanetary disks, yet, their polarisation predictions are not clearly distinguishable. In this talk, I will highlight the role of magnetic fields in protoplanetary disks, present already achieved (indirect) observational constraints, and give an outlook on how to disentangle the sources of continuum polarimetry with ALMA.

 

Observatório Astronómico de Lisboa (Seminar room)

Tapada da Ajuda, 1349-018 Lisboa