Numerical Simulations Concerning the Propagation of Protostellar Jets PDF Download

Author: Anthony Moraghan
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Kanaris Tsinganos
Publisher: Springer Science & Business Media
ISBN: 3642005764
Category : Science
Languages : en
Pages : 662

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It is over a quarter of a century since the discovery of out?ows from young stars. The intervening years have led to remarkable advances in our understanding of this phenomenon. Much of the progress can be attributed to advances in facilities and technologies, including not only larger telescopes but also improved instrument and detector performance. In addition protostellar out?ows have now been imaged from the ground and space at high spatial resolution, e. g. with HST, and at a wide - riety of wavelengths from X-rays to radio waves, revealing more and more about their physics. This veritable revolution in observation has been accompanied by an exponential growth in our ability to numerically simulate the launching and pro- gation of jets. Codes continue to improve: they now incorporate more physics and are increasingly ef?cient through, for example, techniques such as adaptive mesh re?nement and the use of parallel processing in cluster environments. Simulating the launching and propagation of a jet all the way from the vicinity of the star up to 4 several thousand AU (a size range of10 ) is now much closer. In more recent times, developments in observation, theory and numerical s- ulation have been joined by laboratory jet experiments reproducing, on centimetre scales, that which is seen in astrophysics to stretch for several parsecs.

Author: Christophe Sauty
Publisher: Springer
ISBN: 3030141284
Category : Science
Languages : en
Pages : 154

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In 2008, the European FP6 JETSET project ended. JETSET, for Jet, Simulations, Experiments, and Theory, was a joint research network of European expert teams on protostellar jets. The present proceedings are a collection of contributions presenting new results obtained by those groups since the end of the JETSET program. This is also the occasion to celebrate Kanaris Tsinganos’ important contributions to this network and for his enlightening insight in the subject that inspired us all. Some of the former JETSET students are now in the academic world and the subject has never been so alive. So we present here a collection of results of what has been done in the field of protostellar jets in the past ten years from the theoretical, numerical, observational and experimental point of view. We also present new challenges in the field of protostellar jets and what we should expect from the development of new instruments and new numerical codes in the near future. We also gather results on the impact of the study of protostellar jets on other jet studies in particular on relativistic jets. As a matter of fact, it is time for a new network.

Author: Silvano Massaglia
Publisher: Springer Science & Business Media
ISBN: 3540769668
Category : Science
Languages : en
Pages : 182

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The study of the mechanisms that govern origin and propagation of stellar jets involves the treatment of many concurrent physical processes such as gravitation, hydrodynamics and magnetohydrodynamics, atomic physics and radiation. In the past years, an intensive work has been done looking for so- tions of the ideal MHD equations in the steady state limit as well as studying the stability of out?ows in the linear regime. These kind, of approaches have provided a contribution to the understanding of jets that can hardly be ov- estimated. However, the extension of the analyses to the time-dependent and nonlinear regimes could not be avoided, and the MHD numerical simulations were the only mean to achieve this goal. Intherecentyears,considerableprogresseshavebeenmadebythecom- tational?uiddynamiccommunityinthedevelopmentofnumericaltechniques, theso-calledhighresolutionshockcapturingschemes,wellsuitedforthetre- ment of supersonic ?ows with discontinuities. The numerical simulations of astrophysical jets took advantage of these developments; however new physics needed to be incorporated, such as magnetic ?eld e?ects, radiation losses by diluted gases, and proper astrophysics environments. These needs led to the nontrivial extension of the methods devised for the Euler equations of g- dynamics to the magneto-hydrodynamical system. On the other hand, the possibility of carrying out numerical calculations has been greatly facilitated bytheavailability, ononehand,ofpowerfulsupercomputersand,ontheother hand, of fast processors at low cost. Large scale 3D simulations of jets at high resolution are now possible thanks to supercomputers, but also high reso- tion 2D MHD simulations can be performed routinely on desktop computers.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 26

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The link between turbulence in star formatting environments and protostellar jets remains controversial. To explore issues of turbulence and fossil cavities driven by young stellar outflows we present a series of numerical simulations tracking the evolution of transient protostellar jets driven into a turbulent medium. Our simulations show both the effect of turbulence on outflow structures and, conversely, the effect of outflows on the ambient turbulence. We demonstrate how turbulence will lead to strong modifications in jet morphology. More importantly, we demonstrate that individual transient outflows have the capacity to re-energize decaying turbulence. Our simulations support a scenario in which the directed energy/momentum associated with cavities is randomized as the cavities are disrupted by dynamical instabilities seeded by the ambient turbulence. Consideration of the energy power spectra of the simulations reveals that the disruption of the cavities powers an energy cascade consistent with Burgers-type turbulence and produces a driving scale-length associated with the cavity propagation length. We conclude that fossil cavities interacting either with a turbulent medium or with other cavities have the capacity to sustain or create turbulent flows in star forming environments. In the last section we contrast our work and its conclusions with previous studies which claim that jets can not be the source of turbulence.

Author: Christophe Sauty
Publisher:
ISBN: 9783030141295
Category : Astrophysical jets
Languages : en
Pages : 154

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Book Description
In 2008, the European FP6 JETSET project ended. JETSET, for Jet, Simulations, Experiments, and Theory, was a joint research network of European expert teams on protostellar jets. The present proceedings are a collection of contributions presenting new results obtained by those groups since the end of the JETSET program. This is also the occasion to celebrate Kanaris Tsinganos? important contributions to this network and for his enlightening insight in the subject that inspired us all. Some of the former JETSET students are now in the academic world and the subject has never been so alive. So we present here a collection of results of what has been done in the field of protostellar jets in the past ten years from the theoretical, numerical, observational and experimental point of view. We also present new challenges in the field of protostellar jets and what we should expect from the development of new instruments and new numerical codes in the near future. We also gather results on the impact of the study of protostellar jets on other jet studies in particular on relativistic jets. As a matter of fact, it is time for a new network.

Author: Gustavo E. Romero
Publisher: Cambridge University Press
ISBN: 9780521766074
Category : Science
Languages : en
Pages : 440

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Research on all aspects of jet physics has made dramatic progress in recent years. Numerical simulations, semi-analytical models, and observations across the entire electromagnetic spectrum have shed new light on the formation, collimation, propagation, interaction and radiation of astrophysical jets on all scales. The proceedings of IAU Symposium 275 present an up-to-date account of our current knowledge of jets and outflows in different astronomical situations, covering a vast range of phenomena, from protostellar jets up to extragalactic jets. Reviews by the leading scientists in the field set the context for lively discussions and contributed papers on the most varied aspects of jet physics, fostering links between these usually disparate areas.

Author: Jonathan Ferreira
Publisher: Springer
ISBN: 3540680357
Category : Science
Languages : en
Pages : 230

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This volume presents the edited lecture notes of the First JETSET School on Jets from Young Stars: Models and Constraints, held by the Marie Curie Research and Training Network on JET Simulations, Experiments and Theory. The first half of the book is devoted to general observational constraints. The second section is devoted to theoretical knowledge of magneto-hydrodynamic processes pertinent to the jet launching mechanism in young stars.

Author: A.J.L. Fernandes
Publisher: Springer Science & Business Media
ISBN: 9400709994
Category : Science
Languages : en
Pages : 272

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A JENAM 2002 Workshop, Porto, Portugal, 3-5 September 2002

Author: Weiqun Zhang
Publisher:
ISBN:
Category : Astrophysical jets
Languages : en
Pages : 266

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