Protostars and outflows in the NGC 7538 IRS 9 cloud core

摘要: New high-resolution observations of HCO+ J = 1 → 0, H13CN SO (22 11), and continuum with BIMA at 3.4 mm show that the NGC 7538 IRS 9 cloud core is a site active, ongoing star formation. Our reveal least three young bipolar molecular outflows, all ~10,000-20,000 yr old. drives extreme high-velocity outflow observed nearly pole-on. South we find cold protostellar condensation size ~14'' × 6'' mass more than 250 M☉. This center one outflows shows deep redshifted self-absorption in HCO+, suggesting there protostar embedded core, still phase active accretion. source not detected far-infrared, luminosity less 104 L☉; yet, ~60 The profiles toward southern predict accretion rates few times 10-4 to 10-3 M☉ yr-1. Deep VLA 3.6 cm coincides faint thermal source, but no other region has any detectable free-free emission level μJy cm. abundance significantly enhanced hot outflow. A direct comparison estimates from CO for well-characterized predicts an enhancement factor 30, or [HCO+/H2] ≥ 6 10-8.