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Astron. Astrophys. 327, 587-597


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The rise and fall of the NaMgAl stars*

Jocelyn Tomkin1, Bengt Edvardsson2, David L. Lambert1, and Bengt Gustafsson2

1McDonald Observatory and Department of Astronomy, University of Texas, Austin, Texas 78712, USA
2Uppsala Astronomical Observatory, Box 515, S-751 20 Uppsala, Sweden

Received 20 May 1997 / Accepted 19 June 1997

Abstract

We have made new abundance determinations for a sample of NaMgAl stars. These stars, which are a subgroup of the nearby metal-rich field F and G disk dwarfs, were first identified by Edvardsson et al. (1993) on the basis of their apparent enrichment in Na, Mg and Al relative to other elements. The discovery of a planetary companion to the nearby solar type star 51 Peg (Mayor & Queloz 1995) combined with Edvardsson et al.'s earlier identification of 51 Peg as a NaMgAl star highlighted the group's potential importance. Our new analysis, which uses new spectra of higher resolution and better wavelength coverage than the analysis of Edvardsson et al., shows that the Na, Mg and Al abundances of the NaMgAl stars are indistinguishable from those of non-NaMgAl stars with otherwise similar properties. The group thus appears to be spurious.

Our study, which includes 51 Peg, also provides the most complete set of abundances for this star available to date. The new Fe abundance, FORMULA, of 51 Peg confirms earlier measurements of its metal richness. Abundances for 19 other elements, including C, N and O, reveal a fairly uniform enrichment similar to that of Fe and show no evidence of abnormality compared to other metal rich stars of similar spectral type.

Key words: stars: abundances - stars: fundamental parameters - Galaxy: abundances - Galaxy: evolution

*Table 4 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html.

Send offprint requests to: J. Tomkin


© European Southern Observatory (ESO) 1997

Online publication: October 14, 1997
Last change: April 6, 1998
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