  We present 2D Monte Carlo radiative transfer simulations of prestellar cores.
We consider two types of asymmetry: disk-like asymmetry, in which the core is
denser towards the equatorial plane than towards the poles; and axial
asymmetry, in which the core is denser towards the south pole than the north
pole. We limit our treatment to cores with mild asymmetries, which are exposed
directly to the interstellar radiation field or are embedded inside molecular
clouds.
  The isophotal maps of a core depend strongly on the viewing angle. Maps at
wavelengths longer than the peak of the SED (e.g. 850 micron) essentially trace
the column-density. Thus, for instance, cores with disk-like asymmetry appear
elongated when mapped at 850 micron from close to the equatorial plane.
However, at wavelengths near the peak of the SED (e.g. 200 micron), the
emissivity is more strongly dependent on the temperature, and therefore, at
particular viewing angles, there are characteristic features which reflect a
more complicated convolution of the density and temperature fields within the
core.
  These characteristic features are on scales 1/5 to 1/3 of the overall core
size, and so high resolution observations are needed to observe them. They are
also weaker if the core is embedded in a molecular cloud (because the range of
temperature within the core is then smaller), and so high sensitivity is needed
to detect them. Herschel, to be launched in 2007, will in principle provide the
necessary resolution and sensitivity at 170 to 250 micron.
