Outflow and Infall in a Sample of Massive Star-forming Regions

We present single-pointing observations of SiO, HCO+, and H13CO+ from the James Clerk Maxwell Telescope toward 23 massive star-forming regions previously known to contain molecular outflows and ultracompact H II regions. We detected SiO toward 14 sources and suggest that the nondetections in the other nine sources could be due to those outflows being older and without ongoing shocks to replenish the SiO. We serendipitously detected SO 2 toward …