Topics

Key topics

• Polarimetric observations as a tracer of the magnetic fields across the scales and physical environments relevant to the star formation sequence.
• Observations of magnetic fields in filaments, star-forming cores, and protostars: polarized (sub-)millimeter emission from dust and molecules (linear and circular polarization from the Goldreich-Kylafis and Zeeman effects, respectively).
• Polarization of protoplanetary disks and young stars from polarized infrared emission,
• scattered light, and spectropolarimetry.
• Testing solutions to the angular momentum problem and magnetic flux problem in star formation thanks to observations of magnetic and velocity fields (magnetized accretion/ejection, magnetic flux dissipation)

Key questions

• Do polarization observations (via thermal dust continuum emission, star-light absorption, and spectral-lines features) currently allow to establish a global view of the role and evolution of the magnetic field during the star formation sequence ? If not, identify remaining challenges to do so.
• Can we develop new statistical tools (and test them with MHD simulations) to infer magnetic-field strengths and topologies from polarization data?
• Do different indirect tracers (polarized dust emission, polarization of background starlight, and polarization from spectral lines) trace similar magnetic topologies and strengths?
• Are magnetic fields important to remove angular momentum during the star-formation processes, in a time sequence from prestellar cores to pre-main-sequence stars, and contribute to solve the angular momentum problem for star formation?
• Do we have mechanisms for removing magnetic flux during the star formation processes, so as to reconcile the magnetic fluxes observed in stars with the magnetic fields observed in star-forming cores (i.e., solving the “magnetic flux problem”)?
• What novel instrumental and observational techniques can we identify, and how are they relevant to answering key questions across communities?