2010ApJ...718L.181S

We present high-resolution images of the bipolar outflow from W51e2, which are produced from the Submillimeter Array archival data observed for CO(3-2) and HCN(4-3) lines with angular resolutions of 0{farcs}8x0{farcs}6 and 0{farcs}3x0{farcs}2, respectively. The images show that the powerful outflow originates from the protostellar core W51e2-E rather than from the ultracompact H II region W51e2-W. The kinematic timescale of the outflow from W51e2-E is about 1000 yr, younger than the age (∼5000 yr) of the ultracompact H II region W51e2-W. A large mass-loss rate of ∼1x10^–3 M_☉/yr and a high mechanical power of 120 L_☉ are inferred, suggesting that an O star or a cluster of B stars are forming in W51e2-E. The observed outflow activity along with the inferred large accretion rate indicates that at present W51e2-E is in a rapid phase of star formation.