Clustering of young stars in Taurus, Ophiuchus, and the Orion Trapezium

The surface densities of companions, or, equivalently, the two-point correlation functions, of the Taurus, Ophiuchus, and Orion Trapezium star-forming regions (SFRs) display remarkably consistent and systematic behavior. The surface densities are indistinguishable in the binary regime, with a steep power-law dependence on companion separation. The transition between the binary and large-scale clustering regimes is inversely related to the stellar density of the SFR. The large-scale clustering regime can be described by a fractal structure that is roughly the same over the 3 decades of stellar density of these SFRs.