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Astron. Astrophys. 337, 216-222 (1998)
The chemical composition of HD 196944: a carbon and s-process rich, very metal-poor star *
Laimons Za
s 1,
Poul E. Nissen 2 and
William J. Schuster 3
1 Ventspils International Radio Astronomy Center,
Akad
mijas laukums 1, LV-1050
Riga, Latvia (zacs@latnet.lv)
2 Institute of Physics and Astronomy, University of Aarhus,
DK-8000 Aarhus C, Denmark (pen@obs.aau.dk)
3 Observatorio Astronomico Nacional, UNAM, Apartado Postal
877, C.P. 22800 Ensenada, B.C., Mexico
(schuster@bufadora.astrosen.unam.mx)
Received 25 February 1998 / Accepted 19 May 1998
Abstract
An LTE abundance analysis of the post-AGB candidate star
HD 196944 is presented based on high resolution, high S/N
spectra. The radial velocity of HD 196944 is found to be -174 km
s-1 indicating that it belongs to the halo population. The
spectroscopic analysis provides the atmospheric parameters
![[FORMULA]](img1.gif)
= 5250 K, ![[FORMULA]](img2.gif)
= 1.7 (cgs),
![[FORMULA]](img3.gif)
= 1.9 km s-1 corresponding to those
for G2-5 (bright) giants. A low iron abundance, [Fe/H] = -2.45, is
derived confirming the old, low mass nature of the star. With [C/Fe] =
+1.4 and a mean s-process overabundance of [s/Fe] = +1.1 the
peculiar atmospheric composition of HD 196944 is confirmed.
Possible evolutionary stages of HD 196944, that can explain its
atmospheric parameters and composition, are discussed.
Key words: stars:
evolution 
stars:
abundances
stars: chemically
peculiar
stars: AGB and
post-AGB
stars: individual: HD 196944
* Based on observations carried out at the European Southern Observatory, La Silla, Chile
Send offprint requests to: Laimons Zas
Contents
- 1. Introduction
- 2. Observations and data reduction
- 3. Analysis and results
- 3.1. Radial and space velocities
- 3.2. Atmospheric parameters
- 3.3. Abundance analysis
- 4. Discussion and conclusions
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998
Online publication: August 6, 1998
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