New solar twins and the metallicity and temperature scales of the Geneva–Copenhagen Survey

Authors

  • Juliet Datson,

    Corresponding author
    • Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Turku, Finland
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  • Chris Flynn,

    1. Department of Physics and Astronomy, University of Sydney, NSW, Australia
    2. Finnish Centre for Astronomy with ESO, University of Turku, Piikkio, Finland
    3. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, VIC, Australia
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  • Laura Portinari

    1. Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Turku, Finland
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  • Based on observations made with ESO Telescopes at the La Silla Observatory under programme ID 077.D-0525 and from the ESO Science Archive Facility under request number JDATSHCCCA119545 and following.

E-mail: juliet.datson@utu.fi

ABSTRACT

We search for ‘solar twins’ in the Geneva–Copenhagen Survey (GCS) using high-resolution optical spectroscopy. We initially select Sun-like stars from the GCS by absolute magnitude, (by) colour and metallicity close to the solar values. Our aim is to find the stars which are spectroscopically very close to the Sun using line depth ratios and the median equivalent widths and depths of selected lines with a range of excitation potentials. We present the 10 best stars fulfilling combined photometric and spectroscopic criteria, of which six are new twins. We use our full sample of Sun-like stars to examine the calibration of the metallicity and temperature scale in the GCS. Our results give rise to the conclusion that the GCS may be offset from the solar temperature and metallicity for Sun-like stars by 100 K and 0.1 dex, respectively.

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