1. Spectropolarimetry with the green line: Observations and Simulations
A. Bemporad
INAF-Osservatorio Astrofisico di Torino, Italy
ISSI Team on “Coronal Magnetometry”,
First Meeting, 24/02-01/03/2013, Bern

2. OUTLINE Introduction: LCTP for the green line
Spectropolarimetric observations during the 2010 TSE
Simulation of green line polarized emission

3. LCTP calibration
(in collaboration with L. Abbo, G. Capobianco, S. Fineschi, G. Massone)

4. Liquid-crystal Tunable Lyot Filter for Solar Coronagraphy

6. LCTP Perfomances

7. Fe xiv 530.3 spectropolarimetry: observations
(in collaboration with L. Abbo, C. Benna, P. Calcidese, G. Capobianco,
S. Fineschi, G. Massone, M. Romoli)

8. The CorMag was operated during the total solar eclipse of July, 11th on Tatakoto Atoll (French Polynesia)

9. 2010 TSE coronal configuration
K-corona image (filtered) by M. Druckmuller

10. 2010 TSE coronal configuration
SDO/AIA 171
SOHO/LASCO C2 run.diff.

11. 2010 TSE Cormag data
1024X1024 pix, 16 bit/pix, 2MB per image, pix 24um, 6.2’’/pix
31 exposures (exptime 8 sec): 21, 5 and 5 with pol. angles 0°, 60° and 120° resp.

12. 2010 TSE cormag & ekpol data
LASCO/C2 + EKPol
CorMag FeXIV + EIT 304

13. LCTP scan

14. FeXIV line doppler shifts
cormag results
FeXIV line intensity
FeXIV line doppler shifts

15. cormag results Habbal et al. (2010) Fe 13+ ions kinetic temperatures
Prasad et al. (2013)
FeXIV line widths (s)
(after deconvolution with Lyot filter instrumental profile)

16. Pasachoff et al. (2011)
Fe13+ Kinetic Temperature contour levels: Blue: 1.5106 K green: 3.0106 K red : 4.5106 K
K-corona image by M. Drukmuller

17. CoMP-S instrument @ Lomnicky STIT Observatory (SLOVAK R.)

18. LCTP FILTER @ CLIMSO CORONAGRAPH PIc du midi (france)?

19. Fe xiv 530.3 spectropolarimetry: simulations
(in collaboration with L. Abbo, L. Belluzzi, R. Casini, S. Fineschi, P. Judge)

20. The simulation
Simulations of FeXIV green line polarized emission: performed with the numerical code originally developed by P. G. Judge and R. Casini for forbidden lines (see Casini & Judge 1999; Judge & Casini 2001).
Lines assumed to be optically thin, excited by (anisotropic) photospheric radiation + thermal particle collisions.
Assuming that collisional excitation is isotropic → collisional component is unpolarized → collisional depolarization.
Scattering redistribution function Pa’ is proportional to ~ sin2q’ (a2 + b2 cos2q) with q and q’ angles between the field and the direction of the incident and scattered radiation, -a2 / b2 = 1/3 → q VV ~ 54.6° (House 1977).
Direction of linear polarization → projected direction of POS magnetic field, but polarization changes sign at q VV → ambiguity by 90°.

21. First test: centered dipole, no los integration
Q/I (%)
Q/I (%)
qB = ± qVV
qB = ± π/4 +
(dipolar field, isothermal corona at 2ˣ106 K, density profile from Antonucci et al. (2006) for streamer – c.hole interface)

22. First test: centered dipole, no los integration
|U|/I (%)
|U|/I (%)
qB = ±qVV, π ± qVV
qB = kπ/2 +
(dipolar field, isothermal corona at 2ˣ106 K, density profile from Antonucci et al. (2006) for streamer – c.hole interface)

23. Second test: centered dipole, los integration
Q/I (%)
Q/I (%)
qB = ± qVV
qB = ± π/4 +
(dipolar field, isothermal corona at 2ˣ106 K, density profile from Antonucci et al. (2006) for streamer – c.hole interface)

24. Second test: centered dipole, los integration
|U|/I (%)
|U|/I (%)
qB = ±qVV, π ± qVV
qB = kπ/2 +
(dipolar field, isothermal corona at 2ˣ106 K, density profile from Antonucci et al. (2006) for streamer – c.hole interface)

25. third test: shifted dipole, los integration
Q/I (%)
Q/I (%) +
(dipolar field, isothermal corona at 2ˣ106 K, density profile from Antonucci et al. (2006) for streamer – c.hole interface)

26. third test: shifted dipole, los integration
|U|/I (%)
|U|/I (%) +
(dipolar field, isothermal corona at 2ˣ106 K, density profile from Antonucci et al. (2006) for streamer – c.hole interface)

27. fourth test: centered dipole, los integration, loop density
[dipolar field, isothermal corona at 2ˣ106 K, density profile from Antonucci et al. (2006) for streamer – c.hole interface + loop at 109 cm-3 from Ugarte-Urra et al. (2005)]