The physical conditions in Gomez's Hamburger (IRAS 18059-3211), a pre-MS
  rotating disk
  We aim to study the structure, dynamics and physical conditions of Gomez's
Hamburger (IRAS 18059-3211; GoHam). We confirm that GoHam essentially consists
of a flaring disk in keplerian rotation around a young, probably pre-MS star.
We present high resolution SMA maps of 12CO J=2-1, 13CO J=2-1, 12CO J=3-2, and
C17O J=3-2, as well as data on 12CO J=6-5 and the continuum flux at these
wavelengths. Spatial resolutions up to 1" are obtained. Except for the C17O
data, the dynamical ranges are larger than 10. The maps are compared to a
numerical model, which simulates the emission of a rotating disk with the
expected general properties of such objects; a very satisfactory fitting of our
maps is obtained. The meaning and reliability of our results are thoroughly
discussed. Our observations allow measurement of the main properties of GoHam
at scales between ~ 1" (~ 5 10^15 cm, for the assumed distance, 300 pc) and the
total extent of the nebula, 14". We are able to measure the global structure of
the gas-rich disk, which is found to be flaring, and its dynamics, which is
clearly dominated by keplerian rotation, with a very small degree of
turbulence. The combination of different lines, particularly showing different
opacities, allows us to reasonably estimate the distributions of the gas
temperature and density. We clearly find a significant and sharp increase in
temperature at large distances from the equator, accompanied by a decrease in
density of the same order. Finally, we identify and study a condensation in the
southern part of the disk that has no counterparts in the rest of the nebula.
This condensation is quite extended (about 5 10^15 cm), contains a significant
amount of mass (roughly, ~ 6 10^-3 Mo), and seems to be associated with a
detectable distortion of the global rotation kinematics.
