EPoS Contribution |
The Future of Cloud Core Modeling
Jürgen Steinacker Max-Planck-Institut fuer Astronomie, Heidelberg, Germany | |
Currently, the research about the physical mechanisms triggering the
initial collapse of molecular cloud cores is in a phase of transition.
Simple, often spherically symmetric
models are commonly applied to derive
averaged physical properties of the cores from the observations.
They have their merits when being applied to large samples of cores,
when the resolution of core is limited due to the large wavelengths
or the core distance, or when data are to be compared to analytical
predictions.
But for well-resolved nearby cores, both the quality of observational data as well as the simulation resolutions are already at a level where the core data can be analyzed with a more sophisticated model. This will be even more the case when the new telescopes like Herschel and ALMA are online. The step to "next generation modeling" is cumbersome though. In almost all cases, a detailed modeling means to enter a three-dimensional structure space for the gas and dust distribution. The computational effort in calculating the densities and temperatures rises substantially in 3D. Inverse methods become necessary to fight the projection effect due to line-of-sight observations. A multi-wavelengths approach is required to reduce the large parameter space. In order to identify the physical mechanisms triggering the onset of star formation, the key quantity is the velocity field. But exactly the modeling of this vector field makes it necessary to simultaneously consider the chemistry as well as the radiative transfer in continuum and lines with an inverse determination technique. Arguing along this line, I will propose to intensify work based on the combined model approach, which will need modified collaboration structures. We will illustrate this future aspect of the modeling process by discussing our current approach of the low-mass starless core B68. The roundish, well-observed core is proposed to be close to thermo-gravitational balance and exhibits perturbations that might lead to a collapse of the core. We have derived the 3D density and dust temperature structure from a multi-wavelengths inverse radiative transfer modeling of NIR and mm images. The hypothesis of a balance between thermal pressure and gravitation is tested for the non-spherical structure. We report on our current project to assemble the different sources of information and modeling approaches, namely (i) to derive the power spectrum of non-radial pulsations form the density structure, (ii) to calculate the abundances of important species from a chemical network calculation, (iii) to investigate the fate of the core by MHD simulations. (iv) to model the 3D velocity field by line transfer modeling of the observed line emission images. It is argued that the combined model approach has the capabilities to determine the large parameter space of the complex core collapse problem. |