HLRB Project h1342
Outflows and Jets from Young Stellar Objects in Star Cluster
ITA Heidelberg
Proposing Institution
ITA Heidelberg
Project Manager
Dr. Robi Banerjee
Albert-Ueberle-Str. 2
69120 Heidelberg
Abstract
The interstellar medium (ISM) and star forming molecular clouds (MCs)are permeated by turbulent, supersonic gas motions. There is alsostrong evidence that the ISM and the dense cores inside molecularclouds are permeated with magnetic fields. Both phenomena, supersonicturbulence and magnetic fields, are main ingredients in the process ofstar formation. In particular, supersonic motions have the ability tocompress the diffuse gas and produce over-densities which willeventually collapse under there own weight. The final state of thesecollapsing condensates are stars and brown dwarfs of variousmass. Magnetic fields, on the other hand, might slow down or delay thecollapse of molecular cores. These two, somehow competing processeswithin molecular clouds, will shape the important mass distribution ofself-gravitating cores (core mass function, CMF) and stars (initialmass function, IMF).In the proposed project we will study the formation of cores,protostars, and protostellar clusters out of magnetized, turbulentmolecular clouds. It is essential for a complete theory of starformation to understand how overdense cores build up within molecularclouds. The mass distribution, the evolution and clustering, and thecollapse of these cores then determine the initial mass function,which is the main quantification of a star formation theory. We will follow these different stages with comprehensive numerical simulations. As in many successful previous studies we will use the FLASH codewhich is based on an adaptive mesh refinement (AMR) technique allowingus to resolve a large dynamical range in length scales anddensities. Our adaptation of the FLASH code which includes realisticcooling processes by molecular excitations and gas-dust interaction isan appropriate numerical tool to study present day starformation. Recent development of ``sink particles'' for the FLASH codewill furthermore allow us to quantify statistical properties of cores(such as mass and angular momentum distribution) and study theformation of protostellar cluster.Within the proposed project we will study the influence of jets and outflows from young stellar objects (YSO) on their parental molecular cloud. It is known that that low mass YSOs are almost always associated with powerful jets, so called Herbig-Haro objects. These jets are able to drive high velocity outflows which can extend up to several parsec in length scale. So far, little is known of the influence of such jets and outflows on the environment of the youngprotostars. In particular, in a dense cluster environment where many YSOs are found one could imagine that the multiple outflows have a large impact on the structure and evolution of the molecular cloud. For instance, the star formation rate and the turbulent structure of the gas as well as the cloud live time could be strongly influenced by the outflows from YSOs. We are planing to pursue this study with three dimensional magneto-hydrodynamical simulations where we self-consistently model the outflows from collapsed regions. This will be done with the widely used adaptive mesh refinement (AMR) code FLASH which we already used for many successful projects in star formation. Furthermore, we recently developed a treatment to handle accreting protostellar objects (i.e. Lagrangian sink particles) which we will use as sources for YSO outflows. With this powerful tool at hand we are able to study the formation and evolution of young star clusters with realistic mechanical feedback from protostars. A number of important questions of star formation will be addressed within this project: Can outflows maintain the turbulence of the molecular cloud? Can outflows trigger or rather prevent further collapse? Can outflowsinfluence the star formation rate within the molecular cloud? Do they have an influence on the lifetime of the MC?
