Gravitational Infall in the Dense Cores L1527 and L483

Abstract

Lines of N2H+, C3H2, and H2CO show kinematic evidence of gravitational infall in L1527, and probably also in L483. Three trends appear to indicate infall, rather than outflow or rotation: (a) at each protostar position, line peak and centroid velocities get bluer by 0.1–0.3 km s-1 with increasing line optical depth; (b) in maps of C3H2 and H2CO lines, peak and centroid velocities get bluer by a similar amount as positions approach each protostar; and (c) C3H2 line widths in L1527 increase as positions approach the protostar. Also, in both sources H2CO lines show the infall "signature" of spatially concentrated double-peaked profiles, with their blue peaks brighter than their red peaks, as seen previously in B335. Many asymmetric profiles have a single blueshifted peak with a red shoulder, or two peaks with blue/red intensity ratio greater than 3. These are hard to fit with spherical infall models, owing perhaps to the effects of the bipolar outflow. In each source, H2CO line wings show clear evidence of collimated outflow.