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Discovery of Hα satellite emission in a low state of the SW Sextantis star BB Doradus

Authors

  • L. Schmidtobreick,

    Corresponding author
    1. European Southern Observatory, Casilla 19001, Santiago 19, Chile
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  • P. Rodríguez-Gil,

    1. Instituto de Astrofísica de Canarias, Vía Láctea s/n, La Laguna, E-38205 Santa Cruz de Tenerife, Spain
    2. Departamento de Astrofísica, Universidad de La Laguna, La Laguna, E-38203 Santa Cruz de Tenerife, Spain
    3. Isaac Newton Group of Telescopes, Apartado de correos 321, E-38700 Santa Cruz de la Palma, Spain
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  • K. S. Long,

    1. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
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  • B. T. Gänsicke,

    1. Department of Physics, University of Warwick, Coventry CV4 7AL
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  • C. Tappert,

    1. Departamento de Física y Astronomía, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Valparaíso, Chile
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  • M. A. P. Torres

    1. SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, the Netherlands
    2. Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
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Based on observations collected at the European Southern Observatory, Paranal (programme 082.D-0154).

E-mail: lschmidt@eso.org

ABSTRACT

BB Dor was observed during its low state in 2009. Signatures of both binary components are revealed in the average optical spectrum; no signature of accretion is observed. Narrow emission lines of Hα, He i and Na D, as well as TiO absorption troughs, trace the motion of the irradiated secondary star. We detect two additional components in the Hα emission line that share many characteristics of similar ‘satellite’ lines observed in the low state of magnetic cataclysmic variables of AM Her type. It is the first time such emission components are detected for an SW Sex star.

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