The circumestellar disk of the B0 protostar powering the HH 80-81 radio
  jet
  We present subarcsecond angular resolution observations carried out with the
Submillimeter Array (SMA) at 880 $\mu$m centered at the B0-type protostar
GGD27~MM1, the driving source of the parsec scale HH 80-81 jet. We constrain
its polarized continuum emission to be $\lesssim0.8\%$ at this wavelength. Its
submm spectrum is dominated by sulfur-bearing species tracing a rotating
disk--like structure (SO and SO$_2$ isotopologues mainly), but also shows
HCN-bearing and CH$_3$OH lines, which trace the disk and the outflow cavity
walls excavated by the HH 80-81 jet. The presence of many sulfurated lines
could indicate the presence of shocked gas at the disk's centrifugal barrier or
that MM1 is a hot core at an evolved stage. The resolved SO$_2$ emission traces
very well the disk kinematics and we fit the SMA observations using a thin-disk
Keplerian model, which gives the inclination (47$^{\circ}$), the inner
($\lesssim170$ AU) and outer ($\sim950-1300$~AU) radii and the disk's rotation
velocity (3.4 km s$^{-1}$ at a putative radius of 1700 AU). We roughly estimate
a protostellar dynamical mass of 4-18\msun. MM2 and WMC cores show,
comparatively, an almost empty spectra suggesting that they are associated with
extended emission detected in previous low-angular resolution observations, and
therefore indicating youth (MM2) or the presence of a less massive object
(WMC).
