High resolution magnetic field measurements in high-mass star-forming regions

Abstract

Three different scenarios have been proposed to explain the formation of high-mass stars. In one of these scenarios, core accretion, massive stars form through gravitational collapse, which involves disk-assisted accretion to overcome radiation pressure. This scenario is similar to the favored picture of low-mass star-formation, in which magnetic fields are thought to play an important role by removing excess angular momentum, thereby allowing accretion to continue onto the star. However, the role of magnetic fields during the protostellar phase of high-mass star-formation is still a debated topic. In particular, it is still unclear how magnetic fields influence the formation and dynamics of disks and outflows. Most current information on magnetic fields close to high-mass protostars comes from polarized maser emissions, which allow us to investigate the magnetic field on small scales (10s - 1000s AU) by using interferometers, such as EVN, MERLIN, and VLBA. The aim of my Ph.D. was to investigate the magnetic fields in 7 massive star-forming regions by observing the polarized emission of methanol and water masers at milliarcsecond resolution.