Near-IR imaging of the molecular outflows in HH 24-26, L 1634 (HH 240-241), L 1660 (HH 72) and RNO 15 FIR

Narrow-band images in H₂ v=1-0 S(1) (2.122 μm) and adjacent continuum (2.104 μm) are presented of a number of outflows that are driven by young, deeply embedded sources. We report the detection of a H₂ outflow associated with the Class 0 source in the HH 24-26 region, HH 24-MMS, as well as extensive H₂ line emission in the HH 25 and HH 26 CO outflows. In L 1634 a sequence of well-defined molecular bow shocks in the blue-shifted outflow lobe points to variability in the flow velocity, while in L 1660, the poorly aligned H2 knots suggest a wide outflow opening angle and perhaps also a variable flow direction. We also report the discovery of a highly collimated molecular jet associated with the embedded source RNO 15 FIR. These observations provide evidence that molecular outflows from young stars are driven by collimated jets. Indeed, in H₂, we likely observe the molecular shocks which sweep up ambient gas to form the associated CO outflows. We find, however, no obvious correlation between the presumed age of the source of each outflow (based on its IR excess), and the length or luminosity of the flow in H2.