A catalogue of white-light flares observed by Yohkoh

Matthews, SA;van Driel-Gesztelyi, L;Hudson, HS;Nitta, NV
(2003) Astronomy & Astrophysics — Vol. 409, n° 3, p. 1107-1125 (2003)

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  • Matthews, SA
    Author
  • van Driel-Gesztelyi, L
    Author
  • Hudson, HS
    Author
  • Nitta, NV
    Author
Abstract
The aspect camera of the Soft X-ray Telescope (SXT) on Yohkoh provided the first systematic survey of white-light flares from an observatory in space. The observations were made in the Fraunhofer g-band at a pixel size of 2.46 arcsec and a typical sample interval on the order of ten seconds. A total of 28 flares with clear white-light signatures were detected, corresponding to GOES events down to the C7.8 level in one case. Above the X-class threshold, all 5 events observed by SXT were observed in white light, and the maximum average contrast observed was 30% relative to the pre-flare continuum brightness of the flare location. We have made comprehensive comparisons of Yohkoh soft X-ray and hard X-ray data for this list of flares. In addition we compare the properties of the WLF sample to a sample of 31 flares that showed no white-light emission. These comparisons show that while white-light continuum emission has a strong association with hard X-ray emission it is also strongly related to coronal overpressure, as determined from the soft X-ray spectrum, indicating a component with a thermal, rather than non-thermal origin.
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Matthews, S., van Driel-Gesztelyi, L., Hudson, H., & Nitta, N. (2003). A catalogue of white-light flares observed by Yohkoh. Astronomy & Astrophysics, 409(3), 1107-1125. https://doi.org/10.1051/0004-6361:20031187 (Original work published 2003)