We have observed the W75 N massive star forming region in SiO ( J=2–1 & J=1–0 ) at 3 ^ { \prime \prime } -5 ^ { \prime \prime } resolution and in 6 cm , 2 cm , and 7 mm continuum emission at 1.4 ^ { \prime \prime } -0.2 ^ { \prime \prime } resolution .
The abundance ratio of [ SiO ] / [ H _ { 2 } ] \sim 5 - 7 \times 10 ^ { -11 } which is typical for what is expected in the ambient component of molecular clouds with active star formation .
The SiO morphology is diffuse and centered on the positions of the ultracompact HII regions - no collimated , neutral jet was discovered .
The ionized gas surrounding the protostars have emission measures ranging from 1 - 15 \times 10 ^ { 6 } pc cm ^ { -6 } , densities from 0.4 - 5 \times 10 ^ { 4 } cm ^ { -3 } , and derived spectral types of the central ionizing stars ranging from B0.5 to B2 .
Most of the detected sources have spectral indicies which suggest optically thin to moderately optically thick HII regions produced by a central ionizing star .
The spread in ages between the oldest and youngest early-B protostars in the W75 N cluster is 0.1 - 5 \times 10 ^ { 6 } years .
This evolutionary timescale for W75 N is consistent with that found for early-B stars born in clusters forming more massive stars ( M _ { \star } > 25 M _ { \odot } ) .