Astron. Astrophys. 324, 624-628 (1997)

CO J = 10 synthesis images of a dense torus in M 2-9

J. Zweigle ¹, R. Neri ¹, R. Bachiller ², V. Bujarrabal ² and M. Grewing <sup>1

1</sup> Institut de Radio Astronomie Millimétrique (IRAM), 300 Rue de la Piscine, F-38406 Saint Martin d'Hères, France
² Observatorio Astronómico Nacional (I.G.N), Apartado 1143, E-28800 Alcalá de Henares, Madrid, Spain

Received 17 January 1997 / Accepted 18 February 1997

Abstract

We have mapped the CO 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 . 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.

Key words: planetary nebulae: general planetary nebulae: M 2-9 radio lines: ISM stars: mass loss

Send offprint requests to: J. Zweigle

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Contents

• 1. Introduction
• 2. Observations
• 3. Results and discussion
  • 3.1. Continuum
  • 3.2. Morphology and kinematics of the molecular gas
  • 3.3. Spatio-kinematic models for the molecular envelope
  • 3.4. Molecular mass of the torus
• 4. Summary
• Acknowledgements
• References

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998

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