Astrophysical: Sunspots

  • Publication
    Inversions of synthetic umbral flashes: Effects of scanning time on the inferred atmospheres
    Context. The use of instruments that record narrowband images at selected wavelengths is a common approach in solar observations. They allow scanning of a...
  • Publication
    Investigating the Relation between Sunspots and Umbral Dots
    Umbral dots (UDs) are transient, bright features observed in the umbral region of a sunspot. We study the physical properties of UDs observed in sunspots of...
  • Publication
    Limitations of the Ca II 8542 Å Line for the Determination of Magnetic Field Oscillations
    Chromospheric umbral oscillations produce periodic brightenings in the core of some spectral lines, known as umbral flashes. They are also accompanied by...
  • Publication
    Line Asymmetries and the Microstructure of Photospheric Magnetic Fields
    A systematic structuring of magnetic fields over scales much smaller than the mean free path of photospheric photons may be responsible for the observed...
  • Publication
    Long-term evolution of three light bridges developed on the same sunspot
    One important feature of sunspots is the presence of light bridges. These structures are elongated and bright (as compared to the umbra) features that seem to...
  • Publication
    Long-term Variation of Solar Activity by a Dynamo Based on Magnetic Flux Tubes
    We show that cyclic activity and Maunder-type grand minima can be explained by a dynamo driven by the instability of magnetic flux tubes in the overshoot layer...
  • Publication
    Magnetic aspects of the evolution of sunspots
    The spectroscopic determinations of the solar magnetic fields are based on the Zeeman effect observed in relation to a number of absorption lines of the solar...
  • Publication
    Magnetic field fluctuations in the shocked umbral chromosphere
    Context. Umbral chromospheric observations show the presence of magnetoacoustic shocks. Several recent studies have reported magnetic field fluctuations...
  • Publication
    Magnetic field oscillations in sunspots and active regions
    In order to investigate the oscillatory behaviour of the magnetic field in sunspots and pores, full Stokes measurements of 1.56 μm iron lines have been...