The torus, which surrounds the nucleus of M 2-9, has a mean diameter
of about 6''. Its symmetry axis is tilted by with
respect to the plane of the sky. The de-projected expansion velocity
is
, and its kinematical age is about
2100 years assuming a distance of 1 kpc. The lower limit for the
total mass of the molecular gas is estimated to be
, i.e. at least comparable to the ionized mass in the
nebula (Figure 1).
Figure: Maps of the
intensity for the LSR
velocities indicated in the upper left corner of each box
(contours: 72 (
),
144, 216,
288, and
).
The spatial units are offsets in arcseconds with respect to the
assumed position for the central star. Up is north and left is
east. The Gaussian clean beam (
at a position
angle of
) is inserted in the lower left map.
In order to increase the signal to noise ratio in the maps
we smoothed the channels to a velocity resolution of
.
The r.m.s.
noise in the maps is about
.