Structure of the hot molecular core G10.47+0.03
  The physical structure of hot molecular cores, where forming massive stars
have heated up dense dust and gas, but have not yet ionized the molecules,
poses a prominent challenge in the research of high-mass star formation and
astrochemistry. We aim at constraining the spatial distribution of density,
temperature, velocity field, and chemical abundances in the hot molecular core
G10.47+0.03. With the Submillimeter Array (SMA), we obtained high spatial and
spectral resolution of a multitude of molecular lines at different frequencies,
including at 690 GHz. At 345 GHz, our beam size is 0.3", corresponding to 3000
AU. We analyze the data using the three-dimensional dust and line radiative
transfer code RADMC-3D, and myXCLASS for line identification. We find hundreds
of molecular lines from complex molecules and high excitations. Even
vibrationally excited HC15N at 690 GHz is detected. The HCN abundance at high
temperatures is very high. Absorption against the dust continuum occurs in
twelve transitions, whose shape implies an outflow along the line-of-sight.
Outside the continuum peak, the line shapes are indicative of infall. Dust
continuum and molecular line emission are resolved at 345 GHz, revealing
central flattening and rapid radial falloff of the density outwards of 10^4 AU,
best reproduced by a Plummer radial profile of the density. No fragmentation is
detected, but modeling of the line shapes of vibrationally excited HCN suggests
the density to be clumpy. We conclude that G10.47+0.03 is characterized by
beginning of feedback from massive stars, while infall is ongoing. Large gas
masses (hundreds of Msun) are heated to high temperatures, aided by diffusion
of radiation in a high-column-density environment. The increased thermal,
radiative, turbulent, and wind-driven pressure drives expansion in the central
region and is likely responsible for the central flattening of the density.
