Multi-wavelength modelling of the circumstellar environment of the
  massive proto-star AFGL 2591 VLA 3
  We have studied the dust density, temperature and velocity distributions of
the archetypal massive young stellar object (MYSO) AFGL 2591. Given its high
luminosity ($L=2 \times 10^5$ L$_\odot$) and distance ($d=3.3$ kpc), AFGL 2591
has one of the highest $\sqrt{L}/d$ ratio, giving better resolved dust emission
than any other MYSO. As such, this paper provides a template on how to use
resolved multi-wavelength data and radiative transfer to obtain a
well-constrained 2-D axi-symmetric analytic rotating infall model. We show for
the first time that the resolved dust continuum emission from Herschel 70
$\mu$m observations is extended along the outflow direction, whose origin is
explained in part from warm dust in the outflow cavity walls. However, the
model can only explain the kinematic features from CH$_3$CN observations with
unrealistically low stellar masses ($<15$ M$_\odot$), indicating that
additional physical processes may be playing a role in slowing down the
envelope rotation. As part of our 3-step continuum and line fitting, we have
identified model parameters that can be further constrained by specific
observations. High-resolution mm visibilities were fitted to obtain the disc
mass (6 M$_\odot$) and radius (2200 au). A combination of SED and near-IR
observations were used to estimate the luminosity and envelope mass together
with the outflow cavity inclination and opening angles.
