The periodic variations of a white-light flare observed with ULTRACAM

Michail Mathioudakis, Shaun Bloomfield, David Jess, V.S. Dhillon, T.R. Marsh

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


High time resolution observations of a white-light flare on the active star EQ PegB show evidence of intensity variations with a period of ≈10 s. The period drifts to longer values during the decay phase of the flare. If the oscillation is interpreted as an impulsively-excited, standing-acoustic wave in a flare loop, the period implies a loop length of ≈3.4 Mm and ≈6.8 Mm for the case of the fundamental mode and the second harmonic, respectively. However, the small loop lengths imply a very high modulation depth making the acoustic interpretation unlikely. A more realistic interpretation may be that of a fast-MHD wave, with the modulation of the emission being due to the magnetic field. Alternatively, the variations could be due to a series of reconnection events. The periodic signature may then arise as a result of the lateral separation of individual flare loops or current sheets with oscillatory dynamics (i.e., periodic reconnection).
Original languageEnglish
Pages (from-to)323-327
Number of pages5
JournalAstronomy and Astrophysics
Issue number1
Publication statusPublished - 01 Sep 2006


  • waves
  • stars: activity
  • stars: atmospheres
  • stars: flare
  • stars: individual
  • EQ Pegasi

ASJC Scopus subject areas

  • Space and Planetary Science

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