  NGC7538 is a complex massive star-forming region. The region is composed of
several radio continuum sources, one of which is IRS1, a high-mass protostar,
from which a 0.3 pc molecular bipolar outflow was detected. Several maser
species have been detected around IRS1. The CH3OH masers have been suggested to
trace 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 a
disk, but with a different inclination than the Keplerian-disk that is supposed
to be traced by the CH3OH masers. Tracing the magnetic field close to
protostars is fundamental for determining the orientation of the disk/torus.
Recent studies showed that during the protostellar phase of high-mass star
formation the magnetic field is oriented along the outflows and around or on
the surfaces of the disk/torus. The observations of polarized maser emissions
at milliarcsecond resolution can make a crucial contribution to understanding
the orientation of the magnetic field and, consequently, the orientation of the
disk/torus in NGC7538-IRS1. The NRAO Very Long Baseline Array was used to
measure the linear polarization and the Zeeman-splitting of the 22GHz H2O
masers toward NGC7538-IRS1. The European VLBI Network and the MERLIN telescopes
were used to measure the linear polarization and the Zeeman-splitting of the
6.7GHz CH3OH masers toward the same region. We detected 17 H2O masers and 49
CH3OH masers at high angular resolution. We detected linear polarization
emission toward two H2O masers and toward twenty CH3OH masers. The CH3OH
masers, most of which only show a core structure, seem to trace rotating and
potentially infalling gas in the inner part of a torus. Significant
Zeeman-splitting was measured in three CH3OH masers. [...] We also propose a
new description of the structure of the NGC7538-IRS1 maser region.
