Daniel Schertzer | Searcharxiv

arXiv2009

French Roadmap for complex Systems 2008-2009

This second issue of the French Complex Systems Roadmap is the outcome of the Entretiens de Cargese 2008, an interdisciplinary brainstorming session organized over one week in 2008, jointly by RNSC, ISC-PIF and IXXI. It capitalizes on the first roadmap and gathers contributions of more than 70 scientists from major French institutions. The aim of this roadmap is to foster the coordination of the complex systems community on focused topics and questions, as well as to present contributions and challenges in the complex systems sciences and complexity science to the public, political and industrial spheres.

nlin.AO↗

arXiv1999

Turbulent Bipolar Outflows in Young Stellar Objects: Multifractal Universality Classes and Generalized Scaling

We present a study of the scaling properties of bipolar outflows, generic to the circumstellar environment of young stellar objects, and which are generally believed to be magnetohydrodynamically driven. Our work consists of a multifractal analysis of near-infrared light scattered by dust grains in the lobes of seven bipolar nebulae, namely GGD 18, V380 Orionis, LkHα101/NGC 1579, LkHα233, PV Cephei, V645 Cygni (GL 2789), and V633 Cassiopeiae (LkHα198). We argue that these objects pertain to a multifractal universality class, with the corresponding universal parameters averaged over the ensemble yielding alpha= 1.96 +/- 0.02, C_1=0.04 +/- 0.02, and H=0.7 +/- 0.2; these results might suggest that the dynamics of the observed objects are similar. We then proceed to investigate the existence of anisotropy in the scaling of GGD 18 using the Generalized Scale Invariance (GSI) formalism. It is found that differential rotation and stratification are involved in the outflow mechanism. The stratification is believed to be dynamical in nature i.e., gravity is apparently not the dominant stratifying force.

astro-ph↗