Molecular outflows within the filamentary infrared dark cloud G34.43+0.24

Abstract

We present molecular line observations, made with angular resolutions of 2000, toward the filamentary infrared dark cloud G34.43+0.24 using the APEX [CO(3 ! 2), 13CO(3 ! 2), C18O(3 ! 2) and CS(7 ! 6) transitions], Nobeyama 45 m [CS(2 ! 1), SiO(2 ! 1), C34S(2 ! 1), HCO+(1 ! 0), H13CO+(1 ! 0) and CH3OH(2 ! 1) transitions] , and SEST [CS(2 ! 1) and C18O(2 ! 1) transitions] telescopes. We find that the spatial distribution of the molecular emission is similar to that of the dust continuum emission observed with 1100 resolution (Rathborne et al. 2005) showing a filamentary structure and four cores. The cores have local thermodynamic equilibrium masses ranging from 3.3×102 – 1.5×103 M and virial masses from 1.1×103 – 1.5×103 M , molecular hydrogen densities between 1.8 × 104 and 3.9 × 105 cm−3, and column densities > 2.0 × 1022 cm−2; values characteristics of massive star forming cores. The 13CO(3 ! 2) profile observed toward the most massive core reveals a blue profile indicating that the core is undergoing large–scale inward motion with an average infall velocity of 1.3 km s−1 and a mass infall rate of 1.8×10−3 M yr−1. We report the discovery of a molecular outflow toward the northernmost core thought to be in a very early stage of evolution. We also detect the presence of high velocity gas toward each of the other three cores, giving support to the hypothesis that the excess 4.5 μm emission (“green fuzzies”) detected toward these cores is due to shocked gas. The molecular outflows are massive and energetic, with masses ranging from 25 – 80 M , momentum 2.3 – 6.9 × 102 M km s−1, and kinetic energies 1.1 – 3.6 × 103 M km2 s−2; indicating that they are driven by luminous, high-mass young stellar objects.