Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Selective absorption processes as the origin of puzzling spectral line polarization from the Sun

Nature volume 415, pages 403–406 (2002)Cite this article

Abstract

Magnetic fields play a key role in most astrophysical systems, from the Sun to active galactic nuclei1,2,3. They can be studied through their effects on atomic energy levels, which produce polarized spectral lines4,5. In particular, anisotropic radiation ‘pumping’ processes6,7 (which send electrons to higher atomic levels) induce population imbalances that are modified by weak magnetic fields8,9. Here we report peculiarly polarized light in the He I 10,830-Å multiplet observed in a coronal filament located at the centre of the solar disk. We show that the polarized light arises from selective absorption from the ground level of the triplet system of helium, and that it implies the presence of magnetic fields of the order of a few gauss that are highly inclined with respect to the solar radius vector. This disproves the common belief4,10,11 that population imbalances in long-lived atomic levels are insignificant in the presence of inclined fields of the order of a few gauss, and opens up a new diagnostic window for the investigation of solar magnetic fields.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Anisotropic radiation pumping and the Hanle effect.
Figure 2: The solar prominence case versus the solar filament case.
Figure 3: Prominence case: observation versus theory.
Figure 4: Filament case: observation versus theory.

Similar content being viewed by others

References

  1. Parker, E. N. Cosmical Magnetic Fields (Clarendon, Oxford, 1979).

    Google Scholar 

  2. Schrijver, C. J. & Zwaan, C. Solar and Stellar Magnetic Activity (Cambridge Univ. Press, Cambridge, 2000).

    Book  Google Scholar 

  3. Blandford, R. et al. in Astrophysical Spectropolarimetry (eds Trujillo Bueno, J., Moreno-Insertis, F. & Sánchez, F.) 177–223 (Cambridge Univ. Press, Cambridge, 2002).

    Google Scholar 

  4. Stenflo, J. O. Solar Magnetic Fields: Polarized Radiation Diagnostics (Kluwer, Dordrecht, 1994).

    Book  Google Scholar 

  5. Landi Degl'Innocenti, E. in Astrophysical Spectropolarimetry (eds Trujillo Bueno, J., Moreno-Insertis, F. & Sánchez, F.) 1–53 (Cambridge Univ. Press, Cambridge, 2002).

    Google Scholar 

  6. Cohen-Tannoudji, C. & Kastler, A. Optical pumping. Prog. Opt. 5, 3–81 (1966).

    ADS  Google Scholar 

  7. Happer, W. Optical pumping. Rev. Mod. Phys. 44, 169–249 (1972).

    Article  ADS  CAS  Google Scholar 

  8. Hanle, W. Über magnetische Beeinflussung der Polarisation der Resonanzfluoreszenz. Z. Phys. 30, 93–105 (1924).

    Article  ADS  CAS  Google Scholar 

  9. Trujillo Bueno, J. in Advanced Solar Polarimetry: Theory, Observations and Instrumentation (ed. Sigwarth, M.) 161–195 (ASP Conf. Series, Astronomical Society of the Pacific, San Francisco, 2001).

    Google Scholar 

  10. Stenflo, J. O. Quantum interferences, hyperfine structure, and Raman scattering on the Sun. Astron. Astrophys. 324, 344–356 (1997).

    ADS  CAS  Google Scholar 

  11. Stenflo, J. O. in Advanced Solar Polarimetry: Theory, Observations and Instrumentation (ed. Sigwarth, M.) 97–108 (ASP Conf. Series, Astronomical Society of the Pacific, San Francisco, 2001).

    Google Scholar 

  12. Condon, E. U. & Shortley, G. H. The Theory of Atomic Spectra (Cambridge Univ. Press, Cambridge, 1979).

    MATH  Google Scholar 

  13. Stenflo, J. O. & Keller, C. The second solar spectrum: a new window for diagnostics of the Sun. Astron. Astrophys. 321, 927–934 (1997).

    ADS  CAS  Google Scholar 

  14. Lin, H., Penn, M. J. & Kuhn, J. R. He I 10830 line polarimetry: A new tool to probe the filament magnetic fields. Astrophys. J. 493, 978–995 (1998).

    Article  ADS  CAS  Google Scholar 

  15. Stenflo, J. O., Keller, C. & Gandorfer, A. Anomalous polarization effects due to coherent scattering on the sun. Astron. Astrophys. 355, 789–804 (2000).

    ADS  CAS  Google Scholar 

  16. Landi Degl'Innocenti, E. Evidence against turbulent and canopy-like magnetic fields in the solar chromosphere. Nature 392, 256–258 (1998).

    Article  ADS  Google Scholar 

  17. Trujillo Bueno, J. in Solar Polarization (eds Nagendra, K. N. & Stenflo, J. O.) 73–96 (Kluwer Academic, Dordrecht, 1999).

    Book  Google Scholar 

  18. van Ballegooijen, A. A. Solar prominence models. In Encyclopedia of Astronomy and Astrophysics (ed. Murdin, P.) 2703–2707 (Nature Publishing Group, London, 2001); also at 〈http://www.ency-astro.com〉 (2001).

  19. Faurobert-Scholl, M. Hanle effect with partial frequency redistribution. I. Numerical methods and first applications. Astron. Astrophys. 246, 469–480 (1991).

    ADS  CAS  Google Scholar 

  20. Trujillo Bueno, J. & Landi Degl'Innocenti, E. Linear polarization due to lower-level depopulation pumping in stellar atmospheres. Astrophys. J. 482, L183–L186 (1997).

    Article  ADS  Google Scholar 

  21. Martínez Pillet, V. et al. in High Resolution Solar Physics: Theory, Observations, and Techniques (eds Rimmele, T. R., Balasubramaniam, K. S. & Radick, R. R.) 264–272 (ASP Conf. Series 183, Astronomical Society of the Pacific, San Francisco, 1999).

    Google Scholar 

  22. Soltau, D. in The Role of Fine-Scale Magnetic Fields on the Structure of the Solar Atmosphere (eds Schröter, E. H., Vázquez, M. & Wyller, A. A.) 362–366 (Cambridge Univ. Press, Cambridge, 1987).

    Google Scholar 

  23. Radzig, A. A. & Smirnov, B. M. Reference Data on Atoms, Molecules, and Ions (Springer, Berlin, 1985).

    Book  Google Scholar 

  24. Landolfi, M. & Landi Degl'Innocenti, E. Resonance scattering and the diagnostic of very weak magnetic fields in diffuse media. Astron. Astrophys. 167, 200–206 (1986).

    ADS  CAS  Google Scholar 

  25. Landi Degl'Innocenti, E. The determination of vector magnetic fields in prominences from the observations of the Stokes profiles in the D3 line of helium. Solar Phys. 79, 291–322 (1982).

    Article  ADS  Google Scholar 

  26. Landi Degl'Innocenti, E. Polarization in spectral lines: I. A unifying theoretical approach. Solar Phys. 85, 3–31 (1983).

    Article  ADS  Google Scholar 

  27. Bommier, V. Quantum theory of the Hanle effect. Astron. Astrophys. 87, 109–120 (1980).

    ADS  CAS  Google Scholar 

  28. Chandrasekhar, S. Radiative Transfer (Dover, New York, 1960).

    MATH  Google Scholar 

Download references

Acknowledgements

We thank R. Casini and J. O. Stenflo for discussions on quantum electrodynamics and for helping with the presentation of this Letter. The German Vacuum Tower Telescope is operated by the Kiepenheuer Institut at the Observatorio del Teide of the Instituto de Astrofísica de Canarias (IAC). The Tenerife Infrared Polarimeter has been developed by the IAC. We also acknowledge the support of the European Solar Magnetometry Network and of the Spanish Plan Nacional de Astronomía y Astrofísica.

Author information

Authors and Affiliations

  1. Instituto de Astrofísica de Canarias, La Laguna, E-38200, Tenerife, Spain

    J. Trujillo Bueno, M. Collados, L. Merenda & R. Manso Sainz

  2. Dipartimento di Astronomia e Scienza dello Spazio, Università di Firenze, Largo E. Fermi 2, Firenze, I-50125, Italy

    E. Landi Degl'Innocenti & R. Manso Sainz

  3. Dipartimento di Fisica, Università di Trento, Via Sommarive 14, Povo, I-38050, Italy

    L. Merenda

  4. Consejo Superior de Investigaciones Científicas, Madrid, E-28006, Spain

    J. Trujillo Bueno

Authors
  1. J. Trujillo Bueno
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. E. Landi Degl'Innocenti
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. M. Collados
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. L. Merenda
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. R. Manso Sainz
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to J. Trujillo Bueno.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Trujillo Bueno, J., Landi Degl'Innocenti, E., Collados, M. et al. Selective absorption processes as the origin of puzzling spectral line polarization from the Sun. Nature 415, 403–406 (2002). https://doi.org/10.1038/415403a

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/415403a

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing