Dust extinction map of the Nessie filament

We present a high-resolution extinction map of Nessie. We estimate the mean line-mass of Nessie to be 627M_{sun}_/pc and the distance to be 3.5kpc. We find that Nessie shows fragmentation at multiple size scales.

The nearest-neighbour separations of the fragments at all scales are within a factor of 2 of the Jeans' length at that scale. However, the relationship between the mean densities of the fragments and their separations is significantly shallower than expected for Jeans' fragmentation. The relationship is similar to the one predicted for a filament that exhibits a Larson-like scaling between size-scale and velocity dispersion; such a scaling may result from turbulent support.

Based on the number of YSOs in Nessie, we estimate that the star formation rate is 371M_{sun}_/Myr; similar values result if using the number of dense cores, or the amount of dense gas, as the proxy of star formation. The star formation efficiency is 0.017. These numbers indicate that Nessie's star-forming content is comparable to the Solar neighborhood giant molecular clouds like Orion A.