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

doi:10.1086/375017

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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Abstract

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 (L_x/L_bol) = -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 L_x/L_bol, while kT has already substantially cooled.

Original language	English (US)
Pages (from-to)	L51-L54
Journal	Astrophysical Journal
Volume	587
Issue number	1 II
DOIs	https://doi.org/10.1086/375017
State	Published - Apr 10 2003

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/375017

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@article{1dc70636aa9f4bb687c5ff22c3b6caf1,

title = "Coronal X-ray emission from an intermediate-age brown dwarf",

abstract = "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.",

author = "Yohko Tsuboi and Yoshitomo Maeda and Feigelson, {Eric D.} and Garmire, {Gordon P.} and George Chartas and Koji Mori and Pravdo, {Steven H.}",

note = "Funding Information: We express our thanks to the Chandra team for many efforts toward the fabrication of the satellite, launching, daily operation, software developments, and calibrations. We also thank Leisa Townsley for supplying the CTI corrector of ACIS and Kensuke Imanishi and the referee Gibor Basri for useful comments on brown dwarf flares and coronae. This research was supported by NASA contract NAS 8-38252.",

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doi = "10.1086/375017",

language = "English (US)",

volume = "587",

pages = "L51--L54",

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T1 - Coronal X-ray emission from an intermediate-age brown dwarf

AU - Tsuboi, Yohko

AU - Maeda, Yoshitomo

AU - Feigelson, Eric D.

AU - Garmire, Gordon P.

AU - Chartas, George

AU - Mori, Koji

AU - Pravdo, Steven H.

N1 - Funding Information: We express our thanks to the Chandra team for many efforts toward the fabrication of the satellite, launching, daily operation, software developments, and calibrations. We also thank Leisa Townsley for supplying the CTI corrector of ACIS and Kensuke Imanishi and the referee Gibor Basri for useful comments on brown dwarf flares and coronae. This research was supported by NASA contract NAS 8-38252.

PY - 2003/4/10

Y1 - 2003/4/10

N2 - 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.

AB - 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.

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JF - Astrophysical Journal

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

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