Astron. Astrophys. 359, 138-142 (2000)

Chemical composition of HD 179821 (IRAS 19114+0002) ^*

F. Thévenin ¹, M. Parthasarathy ² and G. Jasniewicz <sup>3

1</sup> Observatoire de la Côte d'Azur, B.P. 4229, 06304 Nice Cedex 4, France
² Indian Institute of Astrophysics, Bangalore - 560034, India
³ Université de Montpellier II, GRAAL, UPRESA 5024, CC 72, 34095 Montpellier Cedex 05, France

Received 13 April 1999 / Accepted 18 May 2000

Abstract

A LTE analysis of medium resolution spectra of HD 179821 has been made. Derived atmospheric parameters of HD 179821 are K, and [Fe/H]=-0.5. The position of the star in the H-R diagram, its high radial velocity (V_r=100 km s^-1), its far infrared excess similar to PNe and its chemical composition suggest that HD 179821 is a low mass post-AGB carbon-poor supergiant and not a population I massive red supergiant. The underabundance of carbon and of the s-process element zirconium shows that HD 179821 has not gone through the third dredge-up. We emphasize the similarity of the chemical pattern of the post-AGB star HD 179821 and the C-poor halo PN DDDM-1.

Key words: stars: abundances stars: fundamental parameters stars: individual: HD 179821 stars: AGB and post-AGB

* Based on observations obtained at the Observatoire de Haute-Provence, France

Send offprint requests to: F. Thévenin

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Contents

• 1. Introduction
  • 1.1. Post-AGB stars
  • 1.2. HD 179821
• 2. Observations
• 3. Analysis and results
• 4. Discussion
  • 4.1. Comparison with DDDM-1 and HII-SMC
• 5. Conclusions
• References

© European Southern Observatory (ESO) 2000

Online publication: June 30, 2000
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