The L43 outflow: a wind-driven shell

Molecular outflows driven by Herbig-Haro jets have been well studied, but the initially appealing jet-driven model fails to account for poorly-collimated sources such as L 1551 IRS 5. The outflow from RNO 91, in the L43 dark cloud is another example which shows little evidence for high-velocity wings or bowshock structures, and appears not to be currently driven by a jet (although there is weak evidence for a residual jet on the axis of the flow). Instead our new CO map of L 43 shows that the outflow consists of an expanding shell, and we conclude that a wind catching up with an existing shell -- similar to the situation found in planetary nebulae -- can account for the observations. The outflow is most probably in a late stage of evolution, and is in the process of blowing away its molecular cloud. Finally we compare L 43 with the archetypical L 1551 IRS 5 outflow.