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X-ray emission from a brown dwarf in the Pleiades

Briggs, K. R. ; Pye, J. P.

In: Monthly Notices of the Royal Astronomical Society, 2004, vol. 353, no. 2, p. 673-680

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    Titre
    • X-ray emission from a brown dwarf in the Pleiades
    Auteur
    • Briggs, K. R.. Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
    • Pye, J. P.. Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Monthly Notices of the Royal Astronomical Society, 2004, vol. 353, no. 2, p. 673-680. Blackwell Science Ltd
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:291708
    Summary
    We report on the first detection of X-ray emission from a brown dwarf in the Pleiades, the M7-type Roque 14, obtained using the EPIC detectors on XMM-Newton. This is the first X-ray detection of a brown dwarf intermediate in age between ≈12 and ≈320 Myr. The emission appears persistent, although we cannot rule out flare-like behaviour with a decay time-scale >4 ks. The time-averaged X-ray luminosity of LX≈ 3.3 ± 0.8 × 1027 erg s−1 and its ratios with the bolometric (LX/Lbol≈ 10−3.05) and Hα (LX/LHα≈ 4.0) luminosities suggest magnetic activity similar to that of active main-sequence M dwarfs, such as the M7 old-disc star VB 8, although the suspected binary nature of Roque 14 merits further attention. No emission is detected from four proposed later-type Pleiades brown dwarfs, with upper limits to LX in the range 2.1-3.8 × 1027 erg s−1 and to log (LX/Lbol) in the range −3.10 to −2.91