Advertisement

Observations of the Hanle Effect in the Ca I 4227 and Sr II 4078 Å lines

  • M. Bianda
  • J. O. Stenflo
  • S. K. Solanki
Part of the Astrophysics and Space Science Library book series (ASSL, volume 243)

Abstract

The Hanle effect in the second solar spectrum has been explored with a beam splitter based polarimeter at IRSOL in Locarno. It is the only existing imaging solar polarimeter system that is sensitive to the ultraviolet part of the spectrum, where the scattering-polarization effects are the largest. We discuss results of full vector polarimetry (all four Stokes parameters) in the Ca I 4227 and Sr II 4078 A lines in quiet and active solar regions, and show how the signatures of Hanle depolarization in Stokes Q, Hanle rotation in Stokes U, and the longitudinal Zeeman effect in Stokes V can exhibit strong spatial variations over a few arcsec. We further illustrate how the Hanle observations can be used to derive information on both the spatially unresolved and partially resolved weak magnetic fields outside the supergranulation network.

Key words

polarization scattering Sun: magnetic fields techniques: polarimetric 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bianda, M., Solanki, S.K., Stenflo, J.O.: 1998a, Astron. Astrophys. 331, 760ADSGoogle Scholar
  2. Bianda, M., Stenflo, J.O., Solanki, S.K.: 1998b, Astron. Astrophys. 337, 565ADSGoogle Scholar
  3. Donati, J.-F., Semel, M., Rees, D.E.: 1990, Astron. Astrophys. 232, L1ADSGoogle Scholar
  4. Faurobert-Scholl, M.: 1992, Astron. Astrophys. 258, 521ADSGoogle Scholar
  5. Faurobert-Scholl, M.: 1994, Astron. Astrophys. 285, 655ADSGoogle Scholar
  6. Gandorfer, A.M., Povel, H.P.: 1997, Astron. Astrophys. 328, 381ADSGoogle Scholar
  7. Semel, M., Donati, J.-F., Rees, D.E.: 1993, Astron. Astrophys. 278, 231ADSGoogle Scholar
  8. Stenflo, J.O.: 1982, Solar Phys. 80, 209ADSCrossRefGoogle Scholar
  9. Stenflo, J.O.: 1998, Astron. Astrophys. 338, 301ADSGoogle Scholar
  10. Stenflo, J.O.: 1999, in K.N. Nagendra, J.O. Stenflo (eds.), Solar Polarization, Proc. 2nd SPW, Kluwer, Dordrecht, (in this Volume)Google Scholar
  11. Stenflo, J.O., Baur, T.G., Elmore, D.F.: 1980, Astron. Astrophys. 84, 60ADSGoogle Scholar
  12. Stenflo, J.O., Keller, C.U., Povel, H.P.: 1992, LEST Foundation Techn. Report No. 54, Inst. Theoret. Astrophys., Univ. of OsloGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 1999

Authors and Affiliations

  • M. Bianda
    • 1
  • J. O. Stenflo
    • 2
  • S. K. Solanki
    • 2
  1. 1.Istituto Ricerche Solari Locarno (IRSOL)Locarno-MontiSwitzerland
  2. 2.Institute of AstronomyETH ZentrumZurichSwitzerland

Personalised recommendations