Space and Ground-based Coronal Spectro-polarimetry: Synergies
Silvano Fineschi Alessandro Bemporad, Gerardo Capobianco,
Jessica GirellaINAF –Astrophysical Observatory of Torino, Italy
Jan RybakAISAS-Lomnicky Observatory, Slovakia
Sarah GibsonNCAR-High Altitude Observatory
Toulouse (F)– 4-6 November 2014 The magnetic solar corona as revealed by polarimetry
OUTLINE
• Hanle effect of line linear polarization by resonance scattering asdiagnostics tool to probe the coronal magnetic fields
• 2010 Eclipse observations of the coronal FeXIV 530.3 nm linear polarization.
• Hanle effect interpretation and comparision with froward modeling
• Future spectro-polarimeters for ground- and space-based coronalmagnetometers
Beta
Probing Coronal Magnetism with Space EUV/UV/VIR Polarimetry
PhotosphericVIR lines
Temp. minimum
CIV 150 nmMgII h & k 280 nm
SUMI
HI Ly- 122 nm
CLASP
1.05 Ro
10 Ro
2 RoHI Lyman series, OVI 103.2 nm& Fe IR lines
SolMEX/SCORE
Hanle Effect (tutorial)
Larmour A
Hanle Effect (tutorial)
Larmour A
If Larmour >> A (VIR forbidden lines)
P is // or B
Polarization vector Van Vleck angle
• Linear polarization changes sign
• 3cos2θv -1=0(θv =1/ 3 = 54.7)
Van Vleck angle v = 54.7 deg = v , P=0 < v , LP // B > v , LP B
6
> v
< v
Line Polarization Vector
“Saturated” Hanle effectLarmour >> A
7
FeXIV line 530.3 nm(configuration 3s2 3p) is a magnetic dipole transition:2P3/2 → 2P1/2
Fe XIV 530.3 nm (“Green Line”)
8
Turin - Liquid-crystal Tunable Lyot Filter for Solar Coronagraphy
LC Tunable-filter & Polarimeter Procurement
Turin - Liquid-crystal Tunable Lyot Filter Perfomances
Fine Tuning
0
5
10
15
20
25
30
35
529 529.5 530 530.5 531 531.5
Wavelength (nm)
Tran
smis
sion
(%)
530.3
530.32
530.34
530.36
10
The CorMag was operated during the total solar eclipse of July, 11th 2010 on Tatakoto Atoll (French Polynesia)
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Turin – Coronal Magnetograph - CorMag
2010 Eclipse Results of CorMag
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Model of global solar magnetic field based on extrapolation from phototosphericmagnetograms (averaged over a Carrington rotation do) not include transient structures
Forward modelingvs
CorMag observations
I
I
I
14
CorMAg K- pBPredSci K-pB
Left: Predictice Scence B model extrapolation. Center: Synthetic pB emission from Predictive Science.Right: pB measured by CorMag.
Forward modelingvs
CorMag observations
15
E-corona Polarization Degree (pB/B)
pB FORWARD model pB
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Measured Stokes Paramenters of FeXIV Line (Q/I)
Q FORWARD Model Q
17
Measured Stokes Paramenters of FeXIV Line (U/I)
U FORWARD Model U
E corona: CorMag vs High resolution images
18
I
Left: CorMag spatial resolution 12.4’’. Right M. Druckmuller spatial resolution 1’’.
2
3
4
56
1
«Saturated» Hanle effect in the Coronal FeXIV Line
19
> v < v
Coronal Cavity
20
Left: M. Druckmuller imaging (spatial resolution 1’’).Right: CorMag polarization vector direction (res. 12.4’’).
21SDO/ AIA : (171 Filter)
22
CorMag atLomnicky Stit Observatory (Slovakia)
Hanle Effect (tutorial)
Larmour A
B
UV (permitted) lines: Blos ;losVIR (forbidden) lines: pos
Scattering and Superradial Doppler-dimming effectUV lines: Effect of B on ions v (i.e., kinetic T& T//)
A [107 s-1] ~ 0.88 gJ B [G]
Hanle effect Sensitivity
A FeXIII = 14 Hz BHanle 0.2-2 G
A FeXIII
Proba-3 – ASPIICS Coronagraph
R1
R2
R3R4 R5
R1
R2
R3
R4
R5
SolmeX – COMPASS (ESA M-mission Proposals – 2007 and 2010)
Peter, et al. Exp. Astron. 2011
Summary
Spectro-polarimetry of coronal line-emission in the visible-light wavelength spectrum («forbidden lines») have demonstrated to yield a valuable diagnostics tool of the coronal magnetic field
• New space optics for solar physics (LC-based spectropolarimetry optics)• New ground- and space-based observatories with visible-light spectro-
polarimetry
