Coronal X-ray emission from an intermediate-age brown dwarf

Yohko Tsuboi, Yoshitomo Maeda, Eric D. Feigelson, Gordon P. Garmire, George Chartas, Koji Mori, Steven H. Pravdo

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40 Scopus citations


We report the X-ray detection of the brown dwarf (BD) companion TWA 5B in an ≃ 12 Myr old pre-main-sequence binary system. We clearly resolve the faint companion (35 photons) separated from the X-ray luminous primary by 2″ in a Chandra ACIS image. TWA 5B shows a soft X-ray spectrum with a low plasma temperature of only 0.3 keV and a constant flux during the 3 hr observation, of which the characteristics are commonly seen in the solar corona. The X-ray luminosity is 4 × 1027 ergs s-1 (0.1-10 keV band) or log (Lx/Lbol) = -3.4, Comparing these properties to both younger and older BDs, we discuss the evolution of the X-ray emission in BDs. During their first few megayears, they exhibit high levels of X-ray activity, as seen in higher mass pre-main-sequence stars. The level in TWA 5B is still high at t ≃ 12 Myr in log Lx/Lbol, while kT has already substantially cooled.

Original languageEnglish (US)
Pages (from-to)L51-L54
JournalAstrophysical Journal
Issue number1 II
StatePublished - Apr 10 2003

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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