Astrophysical: Sunspots

  • Publication
    Converging Flows in the Penumbra of a δ Sunspot
    Doppler velocities in the penumbra of a δ-configuration sunspot observed near the limb indicate flows that converge upon the line separating locally positive...
  • Publication
    Decay rates of sunspot groups from 1874 to 1976
    The global behavior and fine structure of the distribution of sunspot decay rates from activity cycle 13 to 20 are presented. It is shown that the distribution...
  • Publication
    Deep probing of the photospheric sunspot penumbra: no evidence of field-free gaps
    Context. Some models for the topology of the magnetic field in sunspot penumbrae predict regions free of magnetic fields or with only dynamically weak fields in...
  • Publication
    Dependence of sunspot photospheric waves on the depth of the source of solar p-modes
    Photospheric waves in sunspots moving radially outward at speeds faster than the characteristic wave velocities have been recently detected. It has been...
  • Publication
    Detailed processes accompanying the decay of an active region
    The decay of a small solar active region is studied with high-resolution magnetograms. The reduction process made it possible to match intensity and magnetic...
  • Publication
    Detection of sea-serpent field lines in sunspot penumbrae
    Aims:We investigate the spatial distribution of magnetic polarities in the penumbra of a spot observed very close to disk center. Methods: High angular and...
  • Publication
    Differential rotation and the SPOT zones
    Doppler measurements, using the Capri magnetograph, of the latitudinal fine structure of the solar differential rotation have been carried out. The positions of...
  • Publication
    Differential rotation of sunspot groups in the period from 1874 through 1976 and changes of the rotation velocity within the solar cycle
    An effort is made to determine the differential rotation of the sun on the basis of the complete sample (1874-1976) of the Greenwich Photoheliographic Results...
  • Publication
    Direct Imaging of Fine Structure in the Chromosphere of a Sunspot Umbra
    High-resolution imaging observations from the Hinode spacecraft in the Ca II H line are employed to study the dynamics of the chromosphere above a sunspot. We...