We present a Submillimeter Array study in the 1.3 mm waveband of the NGC 7538 IRS 1–3 massive star-forming region .
The brightest core in the mm continuum map , MM1 , harbors the IRS 1 young O star .
The core has a gas temperature of about 245 K and shows spatially unresolved emission in complex organic molecules , all typical of a hot molecular core .
Toward MM1 , redshifted absorption is seen in molecular lines with different energies above the ground state .
This absorption probes inward motion of the dense gas toward the central young O star , and the estimated mass accretion rate reaches 10 ^ { -3 } M _ { \odot } yr ^ { -1 } .
Multiple outflows are seen in the CO and ^ { 13 } CO maps .
The gas mass of 50 M _ { \odot } and mass outflow rate of 2.5 \times 10 ^ { -3 } M _ { \odot } yr ^ { -1 } measured in CO line wings are dominated by the MM1 outflow , which is most likely driven by a fast wide-angle wind .
Apart from MM1 , we discover eight new dusty cores , MM2–9 , within a projected distance of 0.35 pc from MM1 .
These cores show no counterpart in infrared or radio continuum emission , while seven of them appear to be forming intermediate- to high-mass stars .
This manifests a deeply embedded star-forming component of the parent cloud of IRS 1–3 .
Apparently we are observing a Trapezium system in formation , and the system is presumably surrounded by a cluster of lower mass stars .