We present 2" to 7" resolution 3 mm continuum and CO(J=1-0) line emission and
near infrared Ks, H2, and [FeII] images toward the massive star forming region
W75 N. The CO emission uncovers a complex morphology of multiple, overlapping
outflows. A total flow mass of greater than 255 Msun extends 3 pc from
end-to-end and is being driven by at least four late to early-B protostars.
More than 10% of the molecular cloud has been accelerated to high velocities by
the molecular flows (> 5.2 km/s relative to v{LSR}) and the mechanical energy
in the outflowing gas is roughly half the gravitational binding energy of the
cloud. The W75 N cluster members represent a range of evolutionary stages, from
stars with no apparent circumstellar material to deeply embedded protostars
that are actively powering massive outflows. Nine cores of
millimeter-wavelength emission highlight the locations of embedded protostars
in W75 N. The total mass of gas & dust associated with the millimeter cores
ranges from 340 Msun to 11 Msun. The infrared reflection nebula and shocked H2
emission have multiple peaks and extensions which, again, suggests the presence
of several outflows. Diffuse H2 emission extends about 0.6 parsecs beyond the
outer boundaries of the CO emission while the [FeII] emission is only detected
close to the protostars. The infrared line emission morphology suggests that
only slow, non-dissociative J-type shocks exist throughout the pc-scale
outflows. Fast, dissociative shocks, common in jet-driven low-mass outflows,
are absent in W75 N. Thus, the energetics of the outflows from the late to
early B protostars in W75 N differ from their low-mass counterparts -- they do
not appear to be simply scaled-up versions of low-mass outflows.Comment: Astrophysical Journal, in press. 23 pages plus 10 figures (jpg
format). See http://www.aoc.nrao.edu/~dshepher/science.shtml for reprint with
full resolution figure
