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tex2html_wrap_inline669 J=1-0 synthesis images of a dense torus in M 2-9

J. Zweigle tex2html_wrap_inline673 , R. Neri tex2html_wrap_inline673 , R. Bachiller tex2html_wrap_inline677 , V. Bujarrabal tex2html_wrap_inline677 , M. Grewing tex2html_wrap_inline673
tex2html_wrap_inline673 Institut de Radio Astronomie Millimétrique (IRAM), 300 Rue de la Piscine, F-38406 Saint Martin d'Hères, France
tex2html_wrap_inline677 Observatorio Astronómico Nacional (I.G.N), Apartado 1143, E-28800 Alcalá de Henares, Madrid, Spain
Abstract: We have mapped the tex2html_wrap_inline669 tex2html_wrap_inline689 emission in the bipolar planetary nebula M 2-9 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 M 2-9, has a mean diameter of about 6''. Its symmetry axis is tilted by tex2html_wrap_inline693 with respect to the plane of the sky. The de-projected expansion velocity is tex2html_wrap_inline695 , 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 tex2html_wrap_inline697 , i.e. at least comparable to the ionized mass in the nebula (Figure 1).

Figure: Maps of the tex2html_wrap_inline669 tex2html_wrap_inline689 intensity for the LSR velocities indicated in the upper left corner of each box (contours: 72 ( tex2html_wrap_inline705 ), 144, 216, 288, and tex2html_wrap_inline713 ). 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 ( tex2html_wrap_inline715 at a position angle of tex2html_wrap_inline717 ) 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 tex2html_wrap_inline719 . The r.m.s. noise in the maps is about tex2html_wrap_inline721 .