An extremely high velocity CO outflow from NGC 7538 IRS 9

New observations of the luminous protostellar object NGC 7538 IRS 9 are presented. Lines of CO J = 3-2 show an extremely high velocity (EHV) red wing, with outflow velocities of 110 km/s. The EHV-emitting region is compact and is centered at a position 5 arcsec east of IRS 9. The emission in lower velocity (classical HV) gas is spatially extended and bipolar. The different spatial distribution and kinematics of the HV and EHV gas imply that the outflow activity of IRS 9 has been discontinuous. The activity which produced the extended HV outflow began roughly 16,000 yr ago, while the activity which produced the EHV gas began roughly 1200 yr ago. The EHV gas has only 3 percent of the mass of the HV gas, but 1.5 times the kinetic energy. 13 refs