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

Julien Sylvestre·Justin Khoury·Shaun Lovejoy·Pierre Bastien·Daniel Schertzer
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Abstract

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.

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Julien Sylvestre, Justin Khoury, Shaun Lovejoy, Pierre Bastien, Daniel Schertzer. 1999-07-30. Turbulent Bipolar Outflows in Young Stellar Objects: Multifractal Universality Classes and Generalized Scaling. https://arxiv.org/abs/astro-ph/9907442

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