NGC 7538S―A HIGH-MASS PROTOSTAR WITH A MASSIVE ROTATING DISK

摘要

We report the detection of a massive rotating disk around the high-mass Class 0 candidate NGC 7538S. The disk is well resolved with the Berkeley-Illinois-Maryland Association array (θ_A = 3″.7) in the 3.4 mm continuum and in H~(13)CN J = 1 → 0. It is seen nearly edge-on and has a size of ～30,000 AU. A young, powerful outflow perpendicular to the rotating disk is mapped in SiO J = 2 → 1 and HCO~+ J = 1 → 0. The dynamical age of the outflow is ≤10,000 yr. The velocity gradient seen in H~(13)CN is consistent with Keplerian rotation. Assuming that the gas is gravitationally bound, the mass of the central object is ～40 solar mass. The mass of the continuum "disk" is ≥100 solar mass and has a luminosity of ～10~4 solar luminosity. H~(13)CN gives a mass of ～400 solar mass for the rotating disk and of ～1000 solar mass for the extended (20″) envelope. Our observations confirm that this is an extremely massive protostar in its earliest stages.