High-sensitivity Millimeter Imaging of Molecular Outflows in Nine Nearby High-mass Star-forming Regions

We present a study of molecular outflows using six lines (including 12CO/13CO/C18O/HCO+(J = 1-0) and SiO/CS(J 2-1)) toward nine nearby high-mass star-forming regions with accurate known distances. This work is based on the high-sensitivity observations obtained 14-m millimeter telescope Purple Mountain Observatory Delingha (PMODLH) observatory. The detection rate 12CO, 13CO, HCO+, CS) 100\%. However, emission SiO was not detected for all sources. full line widths ($\Delta V$) at 3$\sigma$ above baseline these have relationship $\Delta V_{\rm ^{12}CO} > \Delta HCO^{+}} CS} \approx ^{13}CO} ^{18}CO}$. 12CO HCO+ can be used to trace relatively high-velocity outflows, while 13CO CS employed low-velocity outflows. dynamical timescales are longer than those mechanical luminosities, masses, mass-loss rates forces correlated bolometric luminosities their central IRAS