Disk Vertical Structure: Benchmark Test
Models for circumstellar dust+gas disks around pre-main sequence stars are abundant in the astrophysical literature. Although the various models describe different physical circumstances (high/low accretion, intermediate/low mass star, eary/late evolutionary stage etc), many of the differences between the models can also be ascribed to the different model equations and modeling techniques used. The reason is in part due to the complexity of the equations: simplifications need to be made, in order to keep the problem tractable.
Goal of this pageThis page makes available a couple of test setups for vertical structure models of circumstellar disks. The principle goal is to gain concencus on solutions among a large number of people, and thus create a set of benchmark problems that can be used for testing computer programs. Those who have developed such computer programs (for disk structure, or for plane-parallel dust continuum transfer, or both), and are interested in participating in this web-based comparison project, are very welcome to submit their solutions. It is clear that we can only have concensus if as many people as possible contribute their solutions.For the moment the test problems are confined to passive (i.e. non-accreting) flared disks of dust and gas that are irradiated by the central star. We keep the input physics very limited, i.e. we omit physical processes as dust-gas decoupling, dust settling and coagulation, chemistry, heating by radioactive decay etc. We only include radiative equilibrium of the dust grains, i.e. the self-consistent determination of the dust+gas temperature by coupling to frequency- and angle-dependent radiative transfer. The radiative transfer is done in a 1-D vertical plane-parallel slab geometry.
Apart from this benchmark problem homepage, there are a number of others as well. The benchmark project most close to the one here is the 2-D continuum radiative transfer benchmark project maintained by Ilaria Pascucci in Jena, which is focused on protostellar disks as well. In the context of molecular lines there is the benchmark project for molecular line transfer in 1-D, which was initiated at a workshop on radiative transfer in Leiden (1999).
List of programs and authorsThe following programs are currently included in the test setup.
Model 1The first model is meant to test only the radiative transfer and outgoing spectrum of the disk. Only a single radial annulus is taken (so 2-D codes are excluded from this test case). The vertical temperature profile is solved, but the vertical density structure is kept constant. The angle under which the stellar radiation hits the surface is also fixed in this test case. For model 1 we take a relatively small vertical optical depth, so that in principle no technical difficulties (like slow convergence etc) should stand in the way of obtaining a result.The details of the setup can be found in the Setup page for model 1. The results of the test so far can be viewed in the Results page.
Model 2The second model is very similar to model 1, but now for a higher optical depth. This problem may cause difficulties in convergence for transfer codes based on the Lambda Iteration method, or for Monte-Carlo based codes.The details of the setup can be found in the Setup page for model 2. The results of the test so far can be viewed in the Results page.
Model 3The third model is similar to model 2, but for a lower luminosity star. Although this might seem a trivial difference with respect to model 2, the codes in fact disagree on the midplane temperature for model 3 (whereas they agreed for model 2).The details of the setup can be found in the Setup page for model 3. The results of the test so far can be viewed in the Results page.
dullemon@mpia.de |
