What is a faculae in astronomy

Sun torch

Sun flares, also as Faculae (lat. facula = small torch) or Plagues (French bright beaches), are areas on the sun that have increased brightness and temperature (around 7000 ° C) compared to the normal visible surface.

Sun flares are typically located near sunspots, which they often indicate a few days in advance. The mean lifespan is around 15 days; it is therefore usually longer than that of the associated spots. The torches are excited to glow by strongly variable magnetic fields, which are also the cause of the sunspots.

Sun flares spread out flat and in long lines of light in the chromosphere. They can therefore be observed particularly well at the edge zones of the solar disk, where the brightness of the underlying photosphere is already attenuated (edge ​​darkening). Sun flares are best seen in the red light of the hydrogen spectral lines, but also in the calcium wavelengths K2 and K3. The photographic observation takes place by means of spectroheliograms. Occasionally, very bright flares in white light can also be observed in the center of the solar disk, for example if a flare occurs there during observation.

Exact research into solar flares began in the 1950s by Ten Bruggencate and Otto Kiepenheuer. The latter recorded it for the first time at different altitude levels and suspected variable magnetic fields as the cause.


  • Otto Kiepenheuer: The sun (p.89-100). Understandable Science Volume 68, Springer-Verlag, Berlin 1957
  • Allan Fallow et al .: The sun (Chapter Chromosphere and p.37). Time-Life Books, Amsterdam 1992.

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