Solar Physics

, Volume 13, Issue 1, pp 118–125 | Cite as

Photoelectric polarimetry of a dark unipolar sunspot

  • F. -L. Deubner
  • R. Göhring


Photoelectric polarisation measurements in a stable sunspot (type H) with a particularly dark umbra carried out with the Capri magnetograph have been evaluated in terms of Unno's (1956) theory to give the value and direction of the magnetic field vector. A linear increase of the inclination angle with distance from the spot centre up tor ≈ 1.2Rs results, as originally found by Hale and Nicholson (1938) with a different procedure. The field strength decreases from the maximum value (about 3300Γ) to about 15% at the penumbral border, still continuously decreasing outside the spot. The projected field direction deviates considerably from the radial symmetry in several parts of the spot region, but it is in good agreement with that of the overlaying chromospheric structures.


Magnetic Field Field Strength Field Vector Inclination Angle Linear Increase 
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Copyright information

© D. Reidel Publishing Company 1970

Authors and Affiliations

  • F. -L. Deubner
    • 1
  • R. Göhring
    • 1
  1. 1.Fraunhofer InstitutFreiburgGermany

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