Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357

J. Robrade, K. Poppenhaeger, J. H. M. M. Schmitt

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Aims: X-ray emission is an important diagnostics to study magnetic activity in very low mass stars that are presumably fully convective and have an effectively neutral photosphere. Methods: We investigate an XMM-Newton observation of SCR 1845-6357, a nearby, ultracool M 8.5 / T 5.5 dwarf binary. The binary is unresolved in the XMM detectors, but the X-ray emission is very likely from the M 8.5 dwarf. We compare its flaring emission to those of similar very low mass stars and additionally present an XMM observation of the M 8 dwarf VB 10. Results: We detect quasi-quiescent X-ray emission from SCR 1845-6357 at soft X-ray energies in the 0.2-2.0 keV band, as well as a strong flare with a count rate increase of a factor of 30 and a duration of only 10 min. The quasi-quiescent X-ray luminosity of log LX = 26.2 erg/s and the corresponding activity level of log LX/Lbol = -3.8 point to a fairly active star. Coronal temperatures of up to 5 MK and frequent minor variability support this picture. During the flare, which is accompanied by a significant brightening in the near-UV, plasma temperatures of 25-30 MK are observed and an X-ray luminosity of LX = 8 × 1027 erg/s is reached. Conclusions: The source SCR 1845-6357 is a nearby, very low mass star that emits X-rays at detectable levels in quasi-quiescence, implying the existence of a corona. The high activity level, coronal temperatures and the observed large flare point to a rather active star, despite its estimated age of a few Gyr.
Original languageEnglish
JournalAstronomy & Astrophysics
Volume513
Issue numberA12
Publication statusPublished - 01 Apr 2010

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silicon controlled rectifiers
x rays
flares
stars
XMM-Newton telescope
erg
luminosity
temperature
plasma temperature
photosphere
flaring
newton
plasma
detectors

Keywords

  • stars: activity
  • stars: coronae
  • stars: individual: SCR 1845-6357
  • stars: low-mass
  • brown dwarfs
  • X-rays: stars

Cite this

Robrade, J., Poppenhaeger, K., & Schmitt, J. H. M. M. (2010). Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357. Astronomy & Astrophysics, 513(A12).
Robrade, J. ; Poppenhaeger, K. ; Schmitt, J. H. M. M. / Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357. In: Astronomy & Astrophysics. 2010 ; Vol. 513, No. A12.
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abstract = "Aims: X-ray emission is an important diagnostics to study magnetic activity in very low mass stars that are presumably fully convective and have an effectively neutral photosphere. Methods: We investigate an XMM-Newton observation of SCR 1845-6357, a nearby, ultracool M 8.5 / T 5.5 dwarf binary. The binary is unresolved in the XMM detectors, but the X-ray emission is very likely from the M 8.5 dwarf. We compare its flaring emission to those of similar very low mass stars and additionally present an XMM observation of the M 8 dwarf VB 10. Results: We detect quasi-quiescent X-ray emission from SCR 1845-6357 at soft X-ray energies in the 0.2-2.0 keV band, as well as a strong flare with a count rate increase of a factor of 30 and a duration of only 10 min. The quasi-quiescent X-ray luminosity of log LX = 26.2 erg/s and the corresponding activity level of log LX/Lbol = -3.8 point to a fairly active star. Coronal temperatures of up to 5 MK and frequent minor variability support this picture. During the flare, which is accompanied by a significant brightening in the near-UV, plasma temperatures of 25-30 MK are observed and an X-ray luminosity of LX = 8 × 1027 erg/s is reached. Conclusions: The source SCR 1845-6357 is a nearby, very low mass star that emits X-rays at detectable levels in quasi-quiescence, implying the existence of a corona. The high activity level, coronal temperatures and the observed large flare point to a rather active star, despite its estimated age of a few Gyr.",
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Robrade, J, Poppenhaeger, K & Schmitt, JHMM 2010, 'Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357', Astronomy & Astrophysics, vol. 513, no. A12.

Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357. / Robrade, J.; Poppenhaeger, K.; Schmitt, J. H. M. M.

In: Astronomy & Astrophysics, Vol. 513, No. A12, 01.04.2010.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357

AU - Robrade, J.

AU - Poppenhaeger, K.

AU - Schmitt, J. H. M. M.

PY - 2010/4/1

Y1 - 2010/4/1

N2 - Aims: X-ray emission is an important diagnostics to study magnetic activity in very low mass stars that are presumably fully convective and have an effectively neutral photosphere. Methods: We investigate an XMM-Newton observation of SCR 1845-6357, a nearby, ultracool M 8.5 / T 5.5 dwarf binary. The binary is unresolved in the XMM detectors, but the X-ray emission is very likely from the M 8.5 dwarf. We compare its flaring emission to those of similar very low mass stars and additionally present an XMM observation of the M 8 dwarf VB 10. Results: We detect quasi-quiescent X-ray emission from SCR 1845-6357 at soft X-ray energies in the 0.2-2.0 keV band, as well as a strong flare with a count rate increase of a factor of 30 and a duration of only 10 min. The quasi-quiescent X-ray luminosity of log LX = 26.2 erg/s and the corresponding activity level of log LX/Lbol = -3.8 point to a fairly active star. Coronal temperatures of up to 5 MK and frequent minor variability support this picture. During the flare, which is accompanied by a significant brightening in the near-UV, plasma temperatures of 25-30 MK are observed and an X-ray luminosity of LX = 8 × 1027 erg/s is reached. Conclusions: The source SCR 1845-6357 is a nearby, very low mass star that emits X-rays at detectable levels in quasi-quiescence, implying the existence of a corona. The high activity level, coronal temperatures and the observed large flare point to a rather active star, despite its estimated age of a few Gyr.

AB - Aims: X-ray emission is an important diagnostics to study magnetic activity in very low mass stars that are presumably fully convective and have an effectively neutral photosphere. Methods: We investigate an XMM-Newton observation of SCR 1845-6357, a nearby, ultracool M 8.5 / T 5.5 dwarf binary. The binary is unresolved in the XMM detectors, but the X-ray emission is very likely from the M 8.5 dwarf. We compare its flaring emission to those of similar very low mass stars and additionally present an XMM observation of the M 8 dwarf VB 10. Results: We detect quasi-quiescent X-ray emission from SCR 1845-6357 at soft X-ray energies in the 0.2-2.0 keV band, as well as a strong flare with a count rate increase of a factor of 30 and a duration of only 10 min. The quasi-quiescent X-ray luminosity of log LX = 26.2 erg/s and the corresponding activity level of log LX/Lbol = -3.8 point to a fairly active star. Coronal temperatures of up to 5 MK and frequent minor variability support this picture. During the flare, which is accompanied by a significant brightening in the near-UV, plasma temperatures of 25-30 MK are observed and an X-ray luminosity of LX = 8 × 1027 erg/s is reached. Conclusions: The source SCR 1845-6357 is a nearby, very low mass star that emits X-rays at detectable levels in quasi-quiescence, implying the existence of a corona. The high activity level, coronal temperatures and the observed large flare point to a rather active star, despite its estimated age of a few Gyr.

KW - stars: activity

KW - stars: coronae

KW - stars: individual: SCR 1845-6357

KW - stars: low-mass

KW - brown dwarfs

KW - X-rays: stars

M3 - Article

VL - 513

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

IS - A12

ER -