Evidence for Ground-Level Atomic Polarization in the Solar Atmosphere

  • E. Landi Degl’Innocenti
Part of the Astrophysics and Space Science Library book series (ASSL, volume 243)


Recent observations of linear polarization at the limb of the quiet Sun, performed with the high sensitivity polarimeter ZIMPOL (Zürich IMaging PO Larimeter), have revealed a large number of unexpected phenomena and, in particular, have shown the existence of a complicated linear polarization pattern across the NaI doublet and of a sharp polarization peak in the core of the D1 line (Stenflo and Keller, 1996, 1997). These phenomena were interpreted as due to the presence of atomic polarization in the hyperfine-structured ground level 3s 2S1/2 of the Na atom, a finding that contradicts the existence of turbulent and canopy-like magnetic fields in the solar chromosphere (Landi Degl’Innocenti, 1998) . In this paper we review the theoretical aspects of the problem (already presented in an abridged form in the paper just quoted) and we comment on some alternative explanations of the polarization pattern of the Na doublet.

Key words

polarization radiative transfer scattering atomic polarization stars: atmospheres 


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Copyright information

© Springer Science+Business Media Dordrecht 1999

Authors and Affiliations

  • E. Landi Degl’Innocenti
    • 1
  1. 1.Dipartimento di AstronomiaScienza dello SpazioFirenzeItalia

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