Metallicities and activities of southern stars ^*,**

¹ Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802, USA e-mail: jjenkins@astro.psu.edu
² Centre for Astrophysics, University of Hertfordshire, College Lane Campus, Hatfield, Hertfordshire, AL10 9AB, UK

Received: 4 September 2007
Accepted: 4 April 2008

Abstract

Aims. We present the results from high-resolution spectroscopic measurements to determine metallicities and activities of bright stars in the southern hemisphere.

Methods. We measured the iron abundances ([Fe/H]'s) and chromospheric emission indices (log ) of 353 solar-type stars with V = 7.5-9.5. [Fe/H] abundances are determined using a custom χ² fitting procedure within a large grid of Kurucz model atmospheres. The chromospheric activities were determined by measuring the amount of emission in the cores of the strong Caii HK lines.

Results. Our comparison of the metallicity sample to other [Fe/H] determinations was found to agree at the ±0.05 dex level for spectroscopic values and at the ±0.1 dex level for photometric values. The distribution of chromospheric activities is described by a bimodal distribution, agreeing with the conclusions from other works. Also an analysis of Maunder minimum status was attempted, and it was found that 6 ± 4 stars in the sample could be in a Maunder minimum phase of their evolution and hence the Sun should only spend a few per cent of its main sequence lifetime in Maunder minimum.