First results of the Chromospheric LAyer
Spectro-Polarimeter (CLASP2)
Ryohko Ishikawa(1)
David McKenzie(2), Javier Trujillo Bueno(3), Frederic Auchere(4), Ryouhei Kano(1), Donguk Song(1), Masaki Yoshida(1), Toshihiro Tsuzuki(1), Fumihiro Uraguchi(1),
Takenori J. Okamoto(1), Laurel Rachmeler(2), Ken Kobayashi (2), and CLASP2 team
(1) National Astronomical Observatory of Japan, (2) NASA Marshall Space Flight Center, (3) Instituto de Astrofisica de Canarias, (4) Institut d'astrophysique spatiale
1
• The magnetic energy is significant; ~2x106 erg/cm2/sec (Ishikawa+2008)
2
heating and high-frequency waves by magnetic reconnection with pre-existing vertical fields
Implications from MHD simulation (Isobe+2008)
(420 km)
Heigh
t
Field Strength from Stokes inversionz
x1,320 km
x
yContinuum
(e.g., Martinez Gonzalez+2010, Gomory+2010)
Ishikawa+2010
Required energy (Withbroe & Noyes 1977)• QS corona: 3x105 erg/cm2/sec• QS chromosphere: 4x106 erg/cm2/sec
Photospheric Magnetic Fields Revealed by Hinode
Example: Granular-scale horizontal fields in the quiet Sun
Chromospheric Dynamics Revealed by Hinode
3
Ubiquitous jets
Shibata+07
De Pontieu+07Okamoto+07
MHD waves
prominence
spicule
solar disk
Many MHD fundamental processes
1000km
1000km
Growing Demand: Magnetic Field Measurement in Upper Solar Atmosphere
4
Quiet photosphere
(β>1)
Dynamic chromosphere
(β<1)
Hinode observation ©NAOJ
β=1
Hei
ght
[Mm
]
Corona
Photosphere
Gary (2001)
Chromosphere
Plasma β (Pgas/PB)
Present
Next
Magnetic field measurement
UV Spectral Lines: Access to the Base of Corona• Sensitive to physical properties at the layer where the temperature suddenly
increases (upper chromosphere and transition region)
5
• Zeeman diagnostics is limited in UVHI Lya (121 nm)
Mg II h & k (280 nm)
ν
Δ"# =%2m()
Stokes-V (circular polarization)
DwB
DwB
[Exception] Mg II h & k in magnetized regions
-
σ+
σ-
Height [km]
Tem
pera
ture
photospherechromospheretransition region
Scattering Polarization & Hanle Effect
6
Atom
Disk center obs.
NOpolarization
Off-limb obs.
Linear polarization parallel to limb
Linear pol.(Stokes-Q)
Parallel to the limb
Perpendicular to the limb
1D plane-parallel atmosphere
Scattering Polarization & Hanle Effect
7
AtomOff-limb obs.
Linear polarization non-parallel to limb
Linear pol.(Stokes-Q)
Parallel to the limb
Perpendicular to the limb
1D plane-parallel atmosphere
B
Magnetic field modifies the scattering polarization
*+,~"# =%2m().
Hanle effectHanle effect
k2V k2R
k1V k1R
k3
Zeeman effect
�
Theoretical calculation with 1D model atmosphere, Mg II k
Alsina Bellester+2016
B=0G
B=0G
10G 10G20G 20G
Q/I (perpendicular/parallel to the limb) U/I
9
8. . OTNDING OC ES 1VPEQIMENSR-/6. : &) /6. : &
CIENCE 9 ECSIUER IN ( RSEPR( ED MDH HA CD C% DLDH !. ( :L M H% HE D M P
) 1 M MDH HA L MM D HE D MDH D :L M E ED L1 M MDH HA MC 3 E S M
+ 2O EH MDH HA MC MD R E L DC H HL C M LDMDH DH
0 DM- : P CHMH <CDM L DLLDE
04 !/C H HL C D 6P %.E C M H%:HE D M - 4 5 6 M & & NM04 ) !/C H HL C D 6.P M H%:HE D M - G 55 H H NM
Final Goal: Establish a means to diagnose the magnetic field at the base of corona with UV spectro-polarimetry
CLASP CLASP2
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/6. : CIENCE 4IGHLIGHSR :OLAQIMESQ
2IQRS 0ESECSION OF CASSEQING :OL IN
-200 -100 0 100 200X [arcsec]
600
700
800
900
1000
Y (s
olar
radi
us) [
arcs
ec]
-200 -100 0 100 200
600
700
800
900
1000
slit length: 400”
Stokes-Q Stokes-U
-0.10 -0.05 0.00 0.05 0.10
600
700
800
900
Y (s
olar
radi
us) [
arcs
ec]
-0.10 -0.05 0.00 0.05 0.10
600
700
800
900
-0.10 -0.05 0.00 0.05 0.10-0.10 -0.05 0.00 0.05 0.10 -0.10 -0.05 0.00 0.05 0.10-0.10 -0.05 0.00 0.05 0.10
[%]
-4
-2
0
2
4
-4
-2
0
2
4
wavelength [nm]
Clear center-to-limb variation up to 6% in Q/IFluctuating at a few% at ~10” both in Q/I and U/I
Q/I U/IIntensity
HI Lya wing (scattering pol. ONLY)
µ=0.2
Belluzzi+ (2012)
Kano+ (2017)
µ=0.4
Kano+ (2017)
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2IQRS 0ESECSION OF CASSEQING :OL IN
-200 -100 0 100 200X [arcsec]
600
700
800
900
1000
Y (s
olar
radi
us) [
arcs
ec]
-200 -100 0 100 200
600
700
800
900
1000
slit length: 400”
Stokes-Q Stokes-U
wavelength [nm]
Q/I U/IIntensity
No clear center-to-limb variation (CLV) in Q/IFluctuating at a few of 0.1% both in Q/I and U/I
H I Lya core (scattering pol. & Hanle)
-0.10 -0.05 0.00 0.05 0.10
600
700
800
900
Y (s
olar
radi
us) [
arcs
ec]
-0.10 -0.05 0.00 0.05 0.10
600
700
800
900
-0.10 -0.05 0.00 0.05 0.10-0.10 -0.05 0.00 0.05 0.10 -0.10 -0.05 0.00 0.05 0.10-0.10 -0.05 0.00 0.05 0.10
[%]
-0.6
-0.4
-0.2
-0.0
0.2
0.4
0.6
-0.6
-0.4
-0.2
-0.0
0.2
0.4
0.6
Stepan+ (2015)
limb disk center
<B>=15G
<B>~250G
<B>=0G
CLV of spatial average of pol. with 3D MHD model
/6. : CIENCE 4IGHLIGHSR :OLAQIMESQ
Kano+ (2017)
Stepan+2018, Trujillo Bueno+2018
H H M D E H E ODMPMC MC H E DL D
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9 REQUASIONAL 1UIDENCE OF 4ANLE 1 ECS• In Lyα core and Si III, U/I deviates from the positive and negative spatial
distribution due to local scattering as photospheric magnetic flux increases
CLASP/SJ
-100 -50 0 50 100X [arcsec]
600
700
800
900
Y (so
lar ra
dius)
[arcse
c]
-100 -50 0 50 100
600
700
800
900
DCAB
SDO/HMI
-100 -50 0 50 100X [arcsec]
-100 -50 0 50 100
R. Ishikawa et al. (2017)
0.0 0.5 1.0 1.5 2.0Magnetic Flux at Solar Surface (x10 ) [Mx]
0.0
0.2
0.4
0.6
0.8
1.0
Devia
tion f
rom Ex
pecte
d Sca
tterin
g Pola
rizati
on D
C
A
BLya wingSi IIILya core
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Large
Zero
Lya coreHanle at B>10G*
Si IIIHanle at B>60G*
Lya wingNO Hanle
/6. : CIENCE 4IGHLIGHSR :OLAQIMESQ
121.50 121.55 121.60 121.65805
810
815
820
Y (so
lar ra
dius)
[arcse
c]
121.50 121.55 121.60 121.65805
810
815
820
Y (so
lar ra
dius)
[arcse
c]
+
-
+
-
U/I
wavelength [nm]
Q<0
dI/dx=dI/dy=0 Q=0
Q<0
Q>0
Q>0
U<0
U<0
U>0
U>0
U=0
IntensityStokes-Q Stokes-U
y (+Q)
x
μ=1
Q<0
dI/dx=dI/dy=0 Q=0
Q<0
Q>0
Q>0
U<0
U<0
U>0
U>0
U=0
IntensityStokes-Q Stokes-U
y (+Q)
x
μ=1
Stepan & Trujillo Bueno (2012), R. Ishikawa+(2017) *0.2BH
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CLASP2 Instrument
CLASP CLASP2Observables Stokes-I, Q, U Stokes-I, Q, U, V
Spectral Lines Lya (121.6 nm) Mg II h & k at 280.0 nmResolutions 0.01nm (wavelength) & 2-3” (spatial) 0.01nm (wavelength) & 2” (spatial)Slit Length 400” 200”
Science Target Quiet Sun near the limb Quiet Sun near the limb & PlagePol. Precision 0.1% at 3σ
CCD
Primary mirror(Cold Mirror coat)
Magnifier(hyperbolicandfoldmirrors,NDfilter)
Cassegrain telescope
ApertureHeat absorber
Slitjaw Optics (SJ) Spectro-Polarimeter
(SP)
Slit mirrorrotating waveplate
-1st order
+1st order
off-axis parabola
CH1
CH2Spherical Grating
Polarizer
Tsuzuki+ in prep.
CLASP2 Development
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Recovery of CLASP instrument
Vibration test of new structure @ JAXA
Integration & alignment in
NAOJ clean room
Packing of instruments
See poster B28 (Song et al.) about CLASP2 polarization calibration
See Song+ 2018, SPIE for SP alignmentand Yoshida+ 2018, SPIE for telescope alignment
CLASP2 Launch: April 11, 2019 16:51 UT @ WSMR
150 DM- : P CHMH <CDM L DLLDE
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Observation Sequence:[1] 18 sec
Disk center for pol. cal.[2] 155 sec
Plage region[3] 134 sec
Quiet Sun near the limb
Flight Performance:Drift: 1”/minJitter: <±0.1” (P-V)
Coordinated observationHinode, IRIS, DST @ Sac Peak(BBSO)
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/6. : :QELIMINAQ ERTLSR
0ESECSION OF CASSEQING :OL AQOTND G 55 H
[%]Temporally
averaged Q/ITemporally
averaged intensity3.0
1.5
0.0
-1.5
-3.0
Temporally & spatially averaged
I
Q/I
Belluzzi & Trujillo Bueno (2012)
• Wavelength structure of Q/I is consistent with the theoretical prediction (Belluzzi & Trujillo Bueno 2012).– Mg II k shows strong scattering polarization while Mg II h
shows exactly zero polarization at the line center.
slit: 200”
Theoretical calculation(µ=0.1, FAL-C, B=0G)
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/6. : :QELIMINAQ ERTLSR
/ENSEQ SO LIM AQIASION OF 5• Clear CLV in far wings• No clear CLV is in the Mg II k center
and near wings
Pointing B (154s)
Pointing C (134s) Pointing A
Pointing BPointing C
Plage
Further investigation & discussion will be in Rachmeler+ in AGU
Plage
Plage
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/6. : :QELIMINAQ ERTLSR
IGNI CANS 5 OUEQ SHE :LAGE
[%]Temporally
averaged V/ITemporally
averaged intensity2.0
1.0
0.0
-1.0
-2.0
Temporally & spatially averaged
I
V/I
• Induced by the longitudinal Zeeman effect• Many spectral lines (Mg II h & k, Mg II triplet, Mn I, etc….) show V/I
slit: 200”
Summary
• CLASP & CLASP2 Demonstrated that high-precision UV spectro-polarimetery is feasible & detected scattering polarization in UV for the first time
• CLASP2 provided detailed measurements of Mg II h & k polarization spectra– Linear polarization (Q/I & U/I) due to scattering– Circular polarization (V/I) due to Zeeman effect over several spectral lines: enable to
constrain magnetic field structures from lower to upper chromosphere in plage
• For a final goal– Utility of V/I in Mg II h & k for determining the magnetic field vector– Importance of simultaneous observations of Lya and Mg II h & k lines
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