  We report high resolution (1-2 arcsec) imaging of the CO 2-1 line and the
millimeter continuum in the proto-planetary nebula He 3-1475. The observations
reveal the presence of a massive (~0.6 M_sun} envelope of molecular gas around
the origin of the remarkable bipolar jet system seen in optical images with the
HST. The CO kinematics are well modeled by an expanding, bi-conical envelope:
the prominent, high-velocity (~50 km/s) wings seen in single-dish CO spectra
arise where the sides of the bi-cones are projected along the line of sight.
The continuum is detected at 1.3 mm and 2.6 mm and is due to thermal emission
from warm (~80 K) circumstellar dust. The structure, kinematics, and expansion
time of the envelope provide strong evidence for entrainment of the molecular
gas by the high velocity jets. The observations support an evolutionary
scenario in which a period of enhanced mass loss by the central star is
followed by the development of the bipolar jets which burst through the
molecular envelope. The jet-envelope interactions play a crucial role in
shaping the subsequent ionized nebula.
