1997A&A...324..624Z

We have mapped the ¹²CO J=1-0 emission in the bipolar planetary nebula M2-9 using the IRAM interferometer. From the maps we were able to investigate in detail the morphology and the kinematics of the molecular gas. The data are best explained by assuming that the molecular gas is concentrated in an expanding, clumpy torus. The torus, which surrounds the nucleus of M2-9, has a mean diameter of about 6". Its symmetry axis is tilted by 17° with respect to the plane of the sky. The de-projected expansion velocity is 7km/s, and its kinematical age is about 2100years assuming a distance of 1kpc. The lower limit for the total mass of the molecular gas is estimated to be 9x10^–3M_☉, i.e. at least comparable to the ionized mass in the nebula.