The Influence of Coronal EUV Irradiance on the Emission in the Hei10830 Å and D3Multiplets
- 10 April 2008
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 677 (1), 742-750
- https://doi.org/10.1086/528680
Abstract
Two of the most attractive spectral windows for spectropolarimetric investigations of the physical properties of the plasma structures in the solar chromosphere and corona are the ones provided by the spectral lines of the He I 10830 and 5876 Å (or D3) multiplets, whose polarization signals are sensitive to the Hanle and Zeeman effects. However, in order to be able to carry out reliable diagnostics, it is crucial to have a good physical understanding of the sensitivity of the observed spectral line radiation to the various competing driving mechanisms. Here we report a series of off-the-limb non-LTE calculations of the He I D3 and 10830 Å emission profiles, focusing our investigation on their sensitivity to the EUV coronal irradiation and the model atmosphere used in the calculations. We show in particular that the intensity ratio of the blue to the red components in the emission profiles of the He I 10830 Å multiplet turns out to be a good candidate as a diagnostic tool for the coronal irradiance. Measurements of this observable as a function of the distance to the limb and its confrontation with radiative transfer modeling might give us valuable information on the physical properties of the solar atmosphere and on the amount of EUV radiation at relevant wavelengths penetrating the chromosphere from above.This publication has 24 references indexed in Scilit:
- Spectropolarimetric Investigation of the Propagation of Magnetoacoustic Waves and Shock Formation in Sunspot AtmospheresThe Astrophysical Journal, 2006
- Retrieval of the full magnetic vector with the He I multiplet at 1083 nmAstronomy & Astrophysics, 2004
- Magnetic Maps of Prominences from Full Stokes Analysis of the He i D3 LineThe Astrophysical Journal, 2003
- On the Role of the Solar Corona and Transition Region in the Excitation of the Spectrum of Neutral HeliumThe Astrophysical Journal, 1997
- Formation of the Solar 10830 Å LinePublished by Springer Science and Business Media LLC ,1994
- Energy balance in the solar transition region. III - Helium emission in hydrostatic, constant-abundance models with diffusionThe Astrophysical Journal, 1993
- Energy balance in the solar transition region. II - Effects of pressure and energy input on hydrostatic modelsThe Astrophysical Journal, 1991
- Energy balance in the solar transition region. I - Hydrostatic thermal models with ambipolar diffusionThe Astrophysical Journal, 1990
- The determination of vector magnetic fields in prominences from the observations of the Stokes profiles in the D3 line of heliumSolar Physics, 1982
- Magnetic Fields Measured with the 10830 Å HeI LineSymposium - International Astronomical Union, 1971