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NGC7538 is a complex massive star-forming region. The region is composed ofseveral radio continuum sources, one of which is IRS1, a high-mass protostar,from which a 0.3 pc molecular bipolar outflow was detected. Several maserspecies have been detected around IRS1. The CH3OH masers have been suggested totrace a Keplerian-disk, while the H2O masers are almost aligned to the outflow.More recent results suggested that the region hosts a torus and potentially adisk, but with a different inclination than the Keplerian-disk that is supposedto be traced by the CH3OH masers. Tracing the magnetic field close toprotostars is fundamental for determining the orientation of the disk/torus.Recent studies showed that during the protostellar phase of high-mass starformation the magnetic field is oriented along the outflows and around or onthe surfaces of the disk/torus. The observations of polarized maser emissionsat milliarcsecond resolution can make a crucial contribution to understandingthe orientation of the magnetic field and, consequently, the orientation of thedisk/torus in NGC7538-IRS1. The NRAO Very Long Baseline Array was used tomeasure the linear polarization and the Zeeman-splitting of the 22GHz H2Omasers toward NGC7538-IRS1. The European VLBI Network and the MERLIN telescopeswere used to measure the linear polarization and the Zeeman-splitting of the6.7GHz CH3OH masers toward the same region. We detected 17 H2O masers and 49CH3OH masers at high angular resolution. We detected linear polarizationemission toward two H2O masers and toward twenty CH3OH masers. The CH3OHmasers, most of which only show a core structure, seem to trace rotating andpotentially infalling gas in the inner part of a torus. SignificantZeeman-splitting was measured in three CH3OH masers. [...] We also propose anew description of the structure of the NGC7538-IRS1 maser region.

The properties and polarization of the H2O and CH3OH maser environment of NGC7538-IRS1