  Investigating in more detail the previously suggested massive disk scenario
for the High-Mass Protostellar Object IRAS18089-1732, we observed the source in
the 860mum band with the Submillimeter Array in various spectral lines and the
submm continuum emission at (sub-)arcsecond spatial resolution. Fifty spectral
lines from eighteen different species spanning upper level energy states
between 17 and 747K were detected. One of the assumed best tracers for massive
disks, CH3CN, is optically thick and does not allow a further disk
investigation. However, the complex molecule HCOOCH3 appears optically thin and
exhibits a velocity shift across the central core perpendicular to the
emanating outflow. Assuming equilibrium between centrifugal and gravitational
force, the estimated mass for this rotating structure is 16/(sin2(i))Msun (with
i the unknown inclination angle), of the same order as the gas mass derived
from the continuum emission. A temperature estimate based on the CH3CN(19--18)
K-ladder results in ~350K, thus a hot core has already formed in this region.
An analysis of the submm continuum emission reveals even at this high spatial
resolution only one isolated massive dust core without any detectable
companions down to mass limits between 0.2 and 3Msun (depending on the assumed
temperature). Potential implications for the massive cluster formation are
discussed.
