Astron. Astrophys. 337, 253-260 (1998)

A sample of planetary nebulae observed by HIPPARCOS

A. Acker ¹, A. Fresneau ¹, S.R. Pottasch ² and G. Jasniewicz <sup>1, 3

1</sup> Observatoire de Strasbourg, CNRS UMR 7550, 11 rue de l'Université, F-67000 Strasbourg, France
² Kapteyn Astronomical Institute, Groningen University, Postbus 800, 9700 AV Groningen, The Netherlands
³ GRAAL, CC72, Université de Montpellier II, Place Eugène Bataillon, F-34095 Montpellier Cedex 05, France

Received 17 July 1997 / Accepted 18 June 1998

Abstract

By using HIPPARCOS data (magnitudes, parallaxes, proper motions), (1) we determine new values of the apparent luminosity of the central stars of 19 planetary nebulae, (2) we discuss their distance and position on the T/L diagram. By comparison with the distances determined by individual or statistical methods, we see that most of these "ground" distances look overestimated when we trust the HIPPARCOS trigonometric parallaxes. It seems that for compact nebulae, the nebula itself could influence the parallax measurement. In particular, the very small HIPPARCOS distances to SwSt 1 and Hu 2-1 are unexpected and are not trustworthy. Peculiar motions are analyzed, in terms of astrophysical parameters of the binary system A 35, and in relation with asymmetric morphology.

Key words: planetary nebulae: general stars: distances stars: evolution

Send offprint requests to: A. Acker

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Contents

• 1. Introduction
• 2. Magnitudes of the central stars
  • 2.1. Selection of the objects
  • 2.2. HIPPARCOS magnitudes of the nuclei
  • 2.3. Comparison of the HIPPARCOS magnitudes with values from the literature
• 3. Distances
  • 3.1. HIPPARCOS distances
  • 3.2. Comparison with other distances
  • 3.3. Adopted distances
• 4. Position on the HR diagram
• 5. Peculiar motions. The case of A 35
  • 5.1. Orbital parameters of A 35
  • 5.2. Asymmetric morphology
• 6. Conclusions
• References

© European Southern Observatory (ESO) 1998

Online publication: August 6, 1998
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