ALMA observations reveal magnetic fields driving protostar jets

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have captured high-resolution images of twisted magnetic fields driving jets from a forming star, resolving a decades-old astrophysical mystery. The research focused on NGC 1333 IRAS 4A, a young double-star system located in the Perseus molecular cloud approximately 960 light-years from Earth.

As protostars grow by accreting material from a surrounding disk, they must shed excess angular momentum to continue growing. This is achieved by blasting material away in powerful, narrow jets and wider outflows. While scientists long suspected that magnetic fields shaped these jets by twisting into a funnel-like, toroidal geometry, these fields had remained observationally unresolved until now.

By measuring the faint polarization of carbon monoxide gas, the research team, led by Tao-Chung Ching, was able to trace the morphology and strength of the magnetic field. The observations confirmed that the magnetic field wraps around the outflow like a coil, providing direct evidence for the magneto-centrifugal models of star formation.