Emmy Noether Application

Second year
At the end of the first project year the candidate should have finished implementing accreting
sink particles into the numerical scheme. At the beginning of the second year into the project
he or she can then start with the rigorous testing of the model. The test calculations should
be compared to analytic and semi-analytic solutions of accretion problems (e.g. Bondi-Hoyle
accretion) and orbiting problems (two or more orbiting objects with different masses). These
comparison calculations should lead to a first publication showing the capability and limits of
the developed model for protostellar cores. This will also give the PhD candidate the chance
to acquire and/or improve his or her presentation and writing skills. At the same time this
documentation will serve as an individual chapter for his or her PhD thesis.
Third year
At the end of the second year the candidate should have finalised the code development and
testing stage and should then proceed with large scale collapse calculations to study the first
stage of massive protostars. This investigation will be based on a comprehensive parameter
study whose results will constitute the main content of the PhD thesis. As mentioned earlier,
this study should result in the quantification of initial conditions which produce putative massive
stars. Based on characteristic calculations the study should quantify the accretion and
merger history of the newly formed protostars. The performed long-term simulations should
then be used to study possible disc fragmentation, the influence by interacting protostars,
and star-disc encounters on the accretion evolution. The results will then be used to address
the open questions in relation with massive star formation listed above. This project should
result in one or more scientific articles which should be published in established scientific
journals.
The PhD candidates should collaborate closely and exchange design concepts before implementation
to allow for a smooth incorporation of the two projects.
At the end of the third year the PhD candidate should write up the developed techniques
and research results in a thesis work. We will make sure that the prospect candidate can
complete the PhD within the specified three years.
Follow-up projects: Fourth and Fifth year
In the fourth and fifth year into the project the developed sink particle approach to capture accretion
properties of protostellar objects should be extended to calculate feedback by mass
ejection from young stellar objects. Ideally this work should be done by the (former) PhD candidate
who then will be most familiar with the numerical techniques. Almost all young stellar
objects are associated with mass outflows, whether stellar winds or disc-driven jets, whose
influence on the formation of massive stars should be taken into account in a comprehensive
calculation. Unfortunately, our knowledge of the launch mechanism of such gas outflows is
not yet conclusive. Therefore we will conduct a comprehensive parameter study where we
will vary mass outflow rates and jet angles which can then be compared to observations to
limit the physical parameter space.
Furthermore we will study the coupling of magnetic fields to the cloud gas. Magnetic fields
permeate the interstellar medium and are associated with all astrophysical objects. Including
these fields in the calculations will also contribute to our understanding of star formation.
So far the FLASH code can solve the ideal MHD equations which are sufficient to study
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