Spectral Inversion of Multiline Full-Disk Observations of Quiet Sun Magnetic Fields
Abstract
Spectral inversion codes are powerful tools for analyzing spectropolarimetric observations, and they provide important diagnostics of solar magnetic fields. Inversion codes differ according to numerical procedure, approximation of the atmospheric model, and description of radiative transfer. Stokes Inversion based on Response functions (SIR) is an implementation widely used by the solar physics community. It allows one to work with different atmospheric components, where gradients of different physical parameters are possible, e.g., magnetic field strength and velocities. The spectropolarimetric full-disk observations were carried out with the Stokesmeter of the Solar Telescope for Operative Prediction (STOP) at the Sayan Observatory on 3 February 2009, when neither an active region nor any other extended flux concentration was present on the Sun. In this study of quiet Sun magnetic fields, we apply the SIR code simultaneously to 15 spectral lines. A tendency is found that weaker magnetic field strengths occur closer to the limb. We explain this finding by the fact that, close to the limb, we are more sensitive to higher altitudes in an expanding flux tube, where the field strength should be smaller since the magnetic flux is conserved with height. Typically, the inversions deliver two populations of magnetic elements: i) high magnetic field strengths (1500 - 2000 G) and high temperatures (5500 - 6500 K) and ii) weak magnetic fields (50 - 150 G) and low temperatures (5000 - 5300 K).
- Publication:
-
Solar Physics
- Pub Date:
- October 2012
- DOI:
- 10.1007/s11207-012-9981-0
- arXiv:
- arXiv:1203.4522
- Bibcode:
- 2012SoPh..280..355B
- Keywords:
-
- Magnetic fields;
- photosphere;
- Spectral line;
- intensity and diagnostics;
- Polarization;
- optical;
- Center-limb observations;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 10 pages, 6 figures, accepted for Solar Physics