Search for Co Outflows toward a Sample of 69 High-mass Protostellar Candidates: Frequency of Occurrence

A survey for molecular outflows was carried out by mapping the CO line toward a sample of 69 J p 2–1 luminous IRAS point sources. Sixty objects have IRAS luminosities from 10 to 10 L, and are associated with dense gas traced by NH3, identifying them as high-mass star-forming regions. Among 69 sources, 65 sources have data that are suitable for outflow identification. Thirty-nine regions show spatially confined high-velocity wing emission in CO, indicative of molecular outflows. Most objects without identifiable outflows lie within 0 ! l ! where outflow signatures are confused by multiple cloud components along the line of sight. Excluding 26 50 sources with , we found 35 outflows out of 39 sources, which yields an outflow detection rate of 90%. 0 ! l ! 50 Many of the outflows contain masses of more than 10 M and have momenta of a few hundred M km s , at 1