2006ApJ...636..952W

We present interferometric observations of N₂H⁺(1-0) in the starless, dense core L694-2 and compare them to previously published maps of L1544. Both cores are starless, centrally condensed, and show spectral signatures of rotation and collapse. We fit radially averaged spectra using a two-layer infall model and measure the variation of opacity and infall speed in each core. Both functions increase toward the center of each core, but the radial gradients are shallower, and the central values lower, in L694-2. This general behavior is predicted in models of gravitational collapse with thermal plus magnetic support, and the lower values in L694-2 may be due to its lower mass or a slightly earlier evolutionary state. In either case, it appears that both cores will form stars within a few 10⁴ yr.