SPATIAL DISTRIBUTIONS OF YOUNG STARS

We analyze the spatial distribution of young stars in Taurus-Auriga and Upper Sco, as determined from the two-point correlation function (i.e., the mean surface density of neighbors). The corresponding power-law fits allow us to determine the fractal dimensions of each association's spatial distribution, measure the stellar velocity dispersions, and distinguish between the bound binary population and chance alignments of members. We find that the fractal dimension of Taurus is D similar to 1.05 consistent with its filamentary structure. The fractal dimension of Upper Sco may be even shallower (D similar to 0.7), but this fit is uncertain due to the limited area and possible spatially variable incompleteness. We also find that random stellar motions have erased all primordial structure on scales of less than or similar to 0.07 degrees in Taurus and less than or similar to 1.7 degrees in Upper Sco; given ages of similar to 1 and similar to 5 Myr, the corresponding internal velocity dispersions are similar to 0.2 and similar to 1.0 km s(-1), respectively. Finally, we find that binaries can be distinguished from chance alignments at separations of less than or similar to 120 '' (17,000 AU) in Taurus and less than or similar to 75 '' (11,000 AU) in Upper Sco. The binary populations in these associations that we previously studied, spanning separations of 3 ''-30 '', is dominated by binary systems. However, the few lowest mass pairs (M-prim less than or similar to 0.3 M-circle dot) might be chance alignments.