MOLECULAR OUTFLOWS FROM NEWLY FORMED MASSIVE STARS

Abstract

We map 6 massive young stellar objects (YSOs) in the CO J=2–1 line and survey 18 massive YSOs, including the six, in the HCO+ J=1−0, SiO J=2−1, H₂O 6 16 − 5 23 maser, and CH₃OH 7 0 − 6 1 A + maser lines. We detect CO bipolar outflows in all the six mapped sources. Four of them are newly discovered (07299−1651, 21306+5540, 22308+5812, 23133+6050), while 05490+2658 is mapped in the CO J=2–1 line for the first time. The detected outflows are much more massive and energetic than outflows from low-mass YSOs with masses >20 M ⊙ and momenta >300 M⊙ km s −1 . They have mass outflow rates (3−6)×10 −4 M ⊙ yr −1 , which are at least one order of magnitude greater than those observed in low-mass YSOs. We detect HCO+ and SiO line emission in 18 (100%) and 4 (22%) sources, respectively. The HCO + spectra show high-velocity wings in 11 (61%) sources. We detect H₂O maser emission in 13 (72%) sources and 44 GHz CH₃OH maser emission in 8 (44%) sources. Of the detected sources, 5 H₂O and 6 CH₃OH maser sources are new discoveries. 20081+3122 shows high-velocity (>30 km s −1 ) H₂O maser lines. We find good correlations of the bolometric luminosity of the central (proto)star with the mechanical force, mechanical luminosity, and mass outflow rate of molecular outflow in the bolometric luminosity range of 10 −1 −10 6 L ⊙ , and identified 3 intermediate- or high-mass counterparts of Class O objects.