, C. Codella , F. Colomer ,
S. Liechti , C.M. Walmsley 
Observatorio Astronomico Nacional (IGN),
Apartado 1143, E-28800 Alcalá de Henares (Madrid), Spain Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5,
I-50125 Firenze, Italy 
[]Channel maps of the CH 
OH 2 
-1 A 
emission detected
with the IRAM
interferometer, integrated over velocity intervals of
1 km s 
wide.
The white star stands for the coordinates of the central source IRAS2 as
measured by Blake (1996), while the straight line points out the direction of
the
outflow.
The central
LSR velocities for each interval, measured with respect
to the LSR velocity of the ambient gas, are indicated in the upper left corner
of each panel.
The contours placed at the south-east of IRAS2 are due to redshifted
emission, whereas the contours at the north-west are blueshifted
emission. Nevertheless, some overlap of redshifted and blueshifted
emission is observed at low velocities in the south-east lobe
(the left region in the panels at 
0.5 and 1.5 km s ).
The contour levels range from 0.15 to 1.50 Jy km
s /beam by step
of 0.15 Jy km s /beam (1.58 K km s ).
We report high-resolution mapping observations of the
2 
-1 ,
3 -2 , and
5 -4 thermal lines of
CH OH toward the young bipolar
outflow driven by the Class 0 object NGC1333/IRAS2 (see Fig. 1).
Only weak emission has been detected towards the position of the central
object, while strong
methanol lines have been observed towards the endpoints of the outflow lobes,
where the CH OH abundance is
enhanced by a factor 
300.
The methanol emission is confined in two jets, with a collimation factor of
about 20:
redshifted emission comes from the south-east lobe, while blueshifted lines
are detected towards the north-west.
Statistical equilibrium calculations have been used to fit
the relative intensities of the observed transitions.
These lead us to the conclusion that the ambient gas surrounding
the protostar has a density similar to that of
the high velocity gas in the shocked regions
( 10 
cm 
).
Interferometric maps with a resolution of 3 
show that
the blueshifted lobe consists of several ``bullets'' indicating
that episodic mass loss has occurred.
The age estimate is 
2-5 10 
yr.
The high-velocity redshifted emission comes from a structure
which becomes ``V-like'' at velocities close to that of the
ambient gas.
These results fit nicely with recent magnetohydrodynamical models where
a working surface with a cone-like shape
creates elongated naked jets containing bullets in their
interior.
Astronomy & Astrophysics in press e-mail contact: bachiller@oan.es