MCFOST Overview

MCFOST is a 3D continuum and line radiative transfer code based on the Monte Carlo method (plus ray-tracing). It is mainly designed to study the circumstellar environment of young stellar objects. The calculations are done exactly within the limitations of the Monte Carlo noise and machine precision, i.e. no approximation are used in the calculations. The code has been strongly optimized for speed.

MCFOST is primarily designed to study protoplanetary disks. The code can reproduce most of the observations of disks:

  • SEDs
  • scattered light images
  • IR and mm visibilities
  • atomic and molecular line maps

The Monte Carlo method being generic, any complex structure can be handled by MCFOST and its use can be extended to other astrophysical objects. For instance, tests have been performed on infalling envelopes and AGB stars.

Important

The code is not public domain yet but available on request on a collaborative basis, with explicit permissions of the authors (see disclaimers below).

The core of the algorithms are described in Pinte et al. (2006) and Pinte et al. 2009. However the code has been substantially further enhanced, with features that are mainly documented in this documentation. In short, the code computes the temperature and scattering source function everywhere in the disk via a Monte Carlo method: photon packets are propagated stochastically through the model volume following the equations of radiative transfer, and information on their properties is retained along their path. The radiation field, and quantities derived from it (for instance temperature, radiation pressure, etc) are obtained by averaging this “Monte Carlo” information. Observables quantities (SEDs and images) are then obtained via a ray-tracing method, which calculates the output intensities by integrating formally the source function estimated by the Monte Carlo calculations. Full calculations of the polarization are included using the Stokes formalism.

MCFOST also includes a non-LTE line transfer module. The adopted schemes are not yet described in the literature, but the code uses an improved version of the algorithm presented in Hogerheijde & van der Tak (2000). NLTE level population are obtained via iterations between Monte Carlo radiative transfer calculations and statistical equilibrium. To speed up calculations, an initial guess is computed using a 1+1D scheme with short characteristic before the full 2D or 3D calculation. Output spectra and channel maps are calculated via a ray-tracing procedure.

Note

MCFOST is in constant development and this documentation is very likely to be lagging. Please contact Christophe Pinte for the latest updates.

Associated with MCFOST, but separate software, are tools for visualization, grid calculations and model fitting tools for SEDs, images and line emission. These tools allows one to draw robust constraints on the derived parameters.

Warning

Use at your own risk!!! The author does not take any responsibility for the use (or misuse of the code). There might be bugs.

Disclaimers

MCFOST is available on a collaborative basis. Using MCFOST implies that you agree to :

  • offer us (C. Pinte, F. Menard, G. Duchene) co-author right on any resulting publication.
  • NOT distribute MCFOST without our explicit agreement.
  • contact us if you initiate a new scientific project with MCFOST.

Please also acknowledge funding from the Australian Research Council under contracts FT170100040 and DP180104235, from Agence Nationale pour la Recherche (ANR) of France under contract ANR-16-CE31-0013.

The IDL code MCRE (MCFOST Results Explorer) is also available on a collaborative basis. Using MCRE implies to offer M. Perrin co-author right. However its use is deprecated. Instead users are encouraged to use the Python mcfost package, available from github, by M. Perrin, C. Pinte, and S. Wolff.

Slack channel

If you decide to use MCFOST, you should sign up to the slack channel in order to be informed of new releases, bugs. This is also a collaborative space to discuss issues and future developments of MCFOST.