The Nature of the Massive Young Stars in W75 N

We have observed the W75 N massive star forming region in SiO(J=2-1 & J=1-0)at 3" - 5" resolution and in 6 cm, 2 cm, and 7 mm continuum emission at 1.4" -0.2" resolution. The abundance ratio of [SiO]/[H2] is roughly 5-7 x 10^-11which is typical for what is expected in the ambient component of molecularclouds with active star formation. The SiO morphology is diffuse and centeredon the positions of the ultracompact HII regions - no collimated, neutral jetwas discovered. The ionized gas surrounding the protostars have emissionmeasures ranging from 1-15 x 10^6 pc cm^-6, densities from 0.4-5 x 10^4 cm^-3,and derived spectral types of the central ionizing stars ranging from B0.5 toB2. Most of the detected sources have spectral indicies which suggest opticallythin to moderately optically thick HII regions produced by a central ionizingstar. The spread in ages between the oldest and youngest early-B protostars inthe W75 N cluster is 0.1-5 x 10^6 years. This evolutionary timescale for W75 Nis consistent with that found for early-B stars born in clusters forming moremassive stars (Mstar > 25 Msun).