Multiline Stokes-metric Investigations of the Full-disk Solar Magnetic Fields: SIR Inversion Results and Applications to the SOHO/MDI Recalibration Issue

Michael Demidov ISTP, Irkutsk, Russia

Beijing, NAOC, 12 January, 2010

Outline

• Introduction• Recent results of Ulrich et al. (2009) • Stokes-meter FeI 523.3 nm – FeI 525.0 nm

simultaneous observations• Preliminary results of SMAT (FeI 532.4) and

STOP (FeI 525.0) quasi-simultaneous observations

• Statistics analysis of 14 lines• Synthesis and inversion (SIR) results • Conclusions

• Howard, R., Stenflo, J.O. Sol.Ph. 22. 1972• Ulrich, R.K. PASP. 26. 1992• Ulrich, R.K., et al., ApJS. 139. 2002• Tran., T., et al., ApJS. 156. 2005.• Martinez Gonzalez, M.J., et al. A&A. 456. 2006• Socas-Navarro, H., et al. ApJ. 674. 2008• Demidov, M.L., et al., Sol.Ph. 250. 2008• Ulrich, R.K., et al. Sol.Ph. 255, 2009

From Tran, T. PhD Thesis, 2009

Fig.1 from Ulrich et al.(2009)

Fig. 3 from Ulrich et al.(2009)

Fig. 13 from Ulrich et al.(2009)

Ulrich et al.(2009) result

“Using ρ as the center-to-limb angle (CLA), [...] scale factor is

δ−1 = 4.15−2.82 sin2(ρ).

Previously δ−1 = 4.5−2.5 sin2(ρ)

had been used. The new calibration shows that magnetic fields measured by the

MDI system on the SOHO spacecraft are equal to 0.619 ± 0.018 times the true

value at a center-to-limb position 30◦”

List of Spectral Lines

N El EP Lande factor

1 522.84 FeI 4.22 0.97 2 522.99 FeI 3.28 1.50 3 523.29 FeI 2.94 1.30 4 523.46 FeII 3.22 0.87 5 523.54 FeI 4.08 1.20 6 523.73 CrI 4.07 0.82 7 523.98 ScII 1.45 1.00 8 524.25 FeI 3.63 1.00 9 524.38 FeI 4.26 1.50 10 524.70 FeI 0.09 2.00 11 524.76 CrI 0.96 2.5 R 525.02 FeI 0.12 3.0 12 525.06 FeI 2.20 1.5 13 525.35 FeI 3.28 1.5

Stokes I and Stokes V, FeI 523.3 nm

Stokes I and Stokes V, FeI 525.0 nm, wide spectral range

Stokes I and Stokes V, FeI 525.0 nm

Stokes V, FeI 525.0 nm and FeI 523.3 nm = 1.0, B525.0 = - 26.0 G

Stokes V, FeI 525.0 nm and FeI 523.3 nm = 0.56, B525.0 = 11.6 G

RESULTS OF THE COMPARISON WITH DIFFERENT “SLIT” PARAMETERS

[pm] Slit width W [pm] R = B(±8.5pm)/B(± )

±15.53 24.82 0.991 1.271 ± 0.009

±0.8 0.80 0.870 1.018 ± 0.028 ±3.1 1.55 0.977 1.073 ± 0.013±10.1 9.32 0.998 1.027 ± 0.003±17.8 9.32 0.935 1.528 ± 0.030

Preliminary result byM.L.Demidov, H.Q.Zhang, X.F.Wang, R.M.Veretsky:

STOP quasi-simultaneous observations in FeI 532.4 nm and FeI 525.0 nm. 10.01.2009

Conclusions Conclusion 1. The revision of the SOHO/MDI data,

based only on the comparison of magnetic field measurements in the line pair Fe I 523.3 nm and Fe I 525.0 nm is not obvious and new investigations are urgently needed.Conclusion 2. Application of the two-components inversion approach (SIR) to the many spectral lines simultaneously allows to reproduce observationsresults quite well. Conclusion 3. Interpretation of the CLVs of the MSR and other parameters in different combinations of spectral lines is still necessary. But this job need to be done in the future.

Thank You!

Спасибо!