Max Planck Institute for Astronomy - Annual Report 2005

0.05 �
Fig. III.2.8: Simulated 10 µm image of the inner region of a
T-Tauri circumstellar disk with a cleared inner region, seen
under an inclination of 60° (assumed distance: 140 pc). Left:
original image, convolved with a PSF corresponding to a 202
as well as the test of other disks for the existence of similar
gaps will provide valuable constraints on the evolution of
the planet-forming region and thus on the process of planet
formation itself (see Fig. III.2.8 for an illustration of the
feasibility to detect a large inner gap with MatIssE).
The radiative transfer simulations which Figures
III.2.7 and III.2.8 have been performed with the radiative
transfer code MC3D, a 3D continuum radiative transfer
code which combines the most recent Monte Carlo radiative
transfer concepts for both the self-consistent radiative
transfer, i.e., the estimation of spatial dust temperature
distributions, and pure scattering applications, taking into
account the polarization state of the radiation field (Wolf
2003). The code is available for download at www.mpia.
de/homes/swolf/mc3d-public/mc3d-public.html.
Future Prospects
The perspective of applying the inverse 3D radiative
transfer method to other cores is promising. Every additional
image observed at other wavelengths will introduce
new constraints for the unknown parameter, and will thus
increase the accuracy of the determined density structure.
The ultimate goal of applying the method to well-observed
cores, however, will be to address the key question
of early star formation, namely if the considered cores
have in-falling material. The current line observations
provide the molecular line emission flux integrated over
all moving gas cells along the line of sight.
III.2 Radiative Transfer – Link between Simulation and Observation 71
m aperture. Right: Reconstructed image. Configuration: seven
nights of observing time with three axilliary telescopes (ATs)
on Paranal. (MatIssE Science case study)
In the general case, gas motion and emissivity of the
cells can not be disentangled, and the 1D approximation
or shearing layers are assumed to unfold it. Without unfolding
it, infall motion can be mixed up with rotational
motion leaving it undecided if the core shows any sign
for the onset of star formation. This is changed if the core
has been investigated with the new method. Knowing the
full 3D structure in dust density and temperature, the line
of sight-integral can be inverted providing the complete
kinematical information if the considered line is optically
thin and a model for the depletion of the considered molecules
is used. This direct verification of infall motion
would also allow to answer the question if the infall occurs
spherically or through a first phase accretion disk.
(Jürgen Steinacker, Sebastian Wolf, Hubert Klahr,
Cornelis Dullemond, Yaroslav Pavlyuchenkov,
Thomas Henning, Manfred Stickel,
In collaboration with colleagues from
Observatoire de Bordeaux,
Astrophysikalisches Institut Potsdam,
Institut für Astronomie und Astrophysik
der Universität Tübingen,
Steward Observatory of the University of Arizona,
Department of Planetary Sciences of the
University of Arizona and
California Institute of Technology)