Evidence for the nearby F4V star λ Ara as a binary system

Authors

  • K. Fuhrmann,

    Corresponding author
    1. Astronomisches Institut, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
    2. Isaac Newton Group of Telescopes, Apartado 321, E-38700 Santa Cruz de La Palma, Spain
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  • R. Chini,

    1. Astronomisches Institut, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
    2. Facultad de Ciencias, Universidad Católica del Norte, Antofagasta, Chile
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  • V. H. Hoffmeister,

    1. Astronomisches Institut, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
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  • O. Stahl

    1. ZAH, Landessternwarte Heidelberg-Königstuhl, D-69117 Heidelberg, Germany
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E-mail: klaus@ing.iac.es

ABSTRACT

We report on the spectroscopic evidence for the nearby, bright and supposedly single F4V star λ Ara as a binary system. The basic observational tracer is a discrepancy with the Hipparcos-based astrometric surface gravity as opposed to the spectroscopically derived value from the pressure-dependent Mg ib triplet lines. We demonstrate how this discrepancy can be met with an equal-mass secondary hidden in the light of the star’s considerable projected rotational velocity vsin i = 15.5 ± 1.0 km s−1 and we expect this scenario to be testable with high-angular resolution direct imaging observations. A major consequence should be the discovery of other nearby binary systems with a similar architecture.

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