Discovery of a massive SCUBA core with both inflow and outflow motions

We report the discovery of a massive SCUBA core with evidence of inflow and outflow motions. This core is detected by SCUBA at both 450 and 850 μm. Barely resolved by the telescope beam at 450 μm, it has a size of 10, corresponding to 0.28 pc at a distance of 5.7 kpc. The dust temperature is estimated to be ≤ 29 K, the total mass is 820 M⊙ and the average density is 1.1×10 cm in a region with a radius of 5. Follow-up spectral line observations, including HCN (3−2), HCO (3−2), HCO (3−2) and CO (2−1) reveal a typical blue profile which indicates that this core is collapsing. The CO (3−2) line profile is as broad as 38 km/s, indicating outflow motions in this region. This core is approximately 1.5 pc away from the known HII region G25.4NW, but there are no obvious radio, IRAS, MSX or Spitzer sources associated with it. We suggest that this core is at a very early stage of massive star or cluster formation. Subject headings: ISM: clouds–ISM: molecules–dust,extinction–ISM: kinematics and dynamics –stars: formation