Ground-based support ofSOT: Magnetic Vector near
Base of Corona

A. Lagg, S.K. Solanki
Max Planck Institute for Solar System Research

Facilities + Tools of MPS
 VTT, mainly TIP2:

1024x1024 detector, 80" slitlength
Echelle spectrograph, infrared 1.08-1.6 (2.2) μm
spatial resolution 0.35“/pix
S/N: typical 1000, max 5000-10000 observing time at SST (G. Scharmer)
 HeLiX (inversion code for He 10830, ME-based) SPINOR (inversion code for a variety ofatmospheric models)collaboration contact:
lagg@mps.mpg.de, solanki@mps.mpg.deHe I 10830 as magnetic field diagnostic
 Magnetic field: main effect in corona (low plasma β),but magnetic vector known mainly at solar surface.

ÎWe developed He I 10830 Å triplet as a diagnosticof the full magnetic vector near the coronal base,following pioneering work by J. Harvey & D. Hall.
 Fields have been measured in active, flaring &emerging flux regions, pores, spots, loops, quiet
Sun, filaments & prominences (Merenda, Tomczyk),& show oscillations (R. Centeno) Here: a glimpse of the rich variety of He I 10830 Åprofiles, magnetic and dynamic structures.

20000
IObservations& Inversions

15000
10000

 Spectropolarimetry: He I Inversion code: basedon Milne-Eddington
atmosphere, genetic
algorithm, includes
Zeeman, simple versionof Hanle + Paschen-Backeffects

Q/IC

0.002
0.000-0.002

U/IC-0.004
0.006
0.004
0.002
0.000-0.002-0.004-0.006
0.04
0.02
V/IC

10830 Å triplet (TIP +TIP2, VTT, Tenerife).
Line formation isextremely complex, butluckily line is often nearly
optically thin.

0.004

0.00-0.02-0.04
10826

10828
10830
Wavelength [¯]10832Loops in emerging flux region
 Maps of: top: velocity
 middle: field strength
 bottom: inclination +azimuth (lines) Note that measured

values may refer todifferent heights,
depending on formation of
He I 10830 Å Emerging loops are cool &hence well visible in He I
Solanki et al. 2003, Lagg et al. 2004

Structure of Magnetic Loops
Magnetic loops
deduced frommeasurementsof He I 10830 ÅStokes profiles
in an emerging
flux region.
Left projection:
Field strengthRight projection:
Vertical velocity
Solanki et al. 2003

Current sheet & emerging flux
 Maps of: top: velocity
 middle: field strength
 bottom: inclination +azimuth (lines) Note that measured

values may refer todifferent heights,
depending on formation of
He 10830
 Boxed region: encloses
rapid change in polarity
Solanki et al. 2003, Lagg et al. 2004

Electric Current SheetHe I 10830 Å reveals electric current sheet (tangential
discontinuity of magnetic vector) near coronal baseObserved inemerging flux
regionSurface:magnetic fieldstrength (notevalley)
Colour: current
density
Solanki et al. 2003

25

Examples ofcurrent sheets

20 0incl. angle γ [°]015010Multiple current sheets
found, but not very
common0OBSERVATION

13may01.014;observation in one of three formats: 1.) sav

WL_RANGE
10825. 10835. ;WL-range to be used for analysis (may be only a13may01.014,avg.fit=2.38
XPOS0 150;two-elements vector containing xmin,xmax of theYPOS
0 100;two-elements vector containing ymin,ymax of the

atm_archive/atm_13may01.014_v01_1comp/input.ipt
STEPX
1;step size for going from xmin to xmax

STEPY1;step size for going from ymin to ymax
AVERAGE1;if 1 then average observation over the stepx/stepySCANSIZE0;stepsize of multiple scans within one observation
SYNTH0.
;if 1 then create synthetic profile
NOISE0.
;noise level for adding artificial random noise
SMOOTH0;ssmooth-value for profiles and smooth-method:STRAYPOL_AMP 0.0;amplitude for stray-polarization (only used forCCORR
1.
;factor for I (constant continuum correction)
STRAYPOL_CORR 100.0000 B;iteration steps and orientation ofNCOMP
1;number of components
BFIEL
000.000.00
2000.00 4 100 4 ;magnetic field value in Gauss
AZIMU
1.00
-90.0090.00 3 100 3 ;azimut of B-vector [deg]
GAMMA
1.00
0.00
180.00 2 100 2 ;inclination of B-vector [deg]VELOS
0.00 -20000.00 50000.00 110 1 ;line-of-sight velocity in m/s
VDAMP
0.35
0.00
0.70 0 100 1 ;damping constant (Voigt only)
VDOPP
0.100.01
0.70 1 100 1 ;doppler broading (Voigt only)
EZERO
1.000.0010.00 0 100 -1 ;amplitude of components of propagati
SGRAD
1.00-4.00
8.40 1 100 1 ;gradient of source function
ALPHA
0.50
0.01
0.99 0 100 0 ;Filling factor for this component
USE_LINEHe;Lines to be used for this component. This allows toIQUV_WEIGHT 1. 1. 1. 1. 1. 1. 1. 1.
;4-element vector defining relative weighting o
WGT_FILE
he_default.wgt ;file with WL-dependent weighting function for IQUVPROFILE
voigt;functional form for pi- and sigma components ofMAGOPT
1 1;include magneto-optical effects (dispersionUSE_GEFF
1 1;use effective Lande factor (=1) or real Zeeman
CODEFORTRAN;PIKAIA code to use. Available: FORTRAN (=fast) orMETHOD0;minimization method: PIKAIA or POWELL (fast)NCALLS
400 00;number of iterations in PIKAIA routine / max.

90

1502520 0015lines: azimuth. anglex (Voigt prof

80

100
7050
6001005010

152025050
6070

80

90x [pix]/aznar/irpolar/linefit/sav/13may01.014_v01_1comp.pikaia.sav

100

Downflows: multi-component
Flaring Region He 10830
1.0Supersonic downflowsare very common

2.0

0.9

I/IC

0.8
1.0

weight I

1.50.7

 Every region has locations

with 2-4 magnetic
components in 1 pixel.

 1 comp nearly at rest, thefine structure (field may
show different inclinations
for different velocity
components)

Sasso [2006]

0.5

0.0

0.006

2.0

1.5

0.002
0.000

1.0

−0.002−0.0040.5−0.006
0.0

10826

10828

10830
10832
Wavelength [Å]10834weight V

 Presence of unresolved

0.50.004

V/ICothers exhibit strongly
supersonic downflows(Mach 2, 4, 7).

0.6Example: 2-component Downflows
very common feature:
downflows of up to 60 km/s
Aznar Cuadrado [2005],
Lagg [2006]

He 1083 inversion +genetic algorithm(PIKAIA):
allows the retrieval ofmagnetic field vector forslow and fast component
Slow Component:
VLOS
B-620 m/s 520 G

Incl.
33°

Azim.
-14°

Fast Component:
VLOS
B
24900 m/s 730 G

Incl.
67°

Azim.
10°

Sunspots
Photosphere
Upperchromosphere
Si I can be used to align HeI data with SOT!
Note higher noiseand higher
oscillation amplitudein chromosphere
Orozco et al. 2005Canopy measurement
He 10830
Chromosphere(He 10830)
19oct05.002, WL 10830.355−10830.737 A

TIP2:
Si 10827 & He 10830
25000
20000
quiet
sun + network field
15000
RMS
noise 5E-430

1.00.8

151.0

30

0.2

0.8

25

150

0.6

10

VLOS

150./sav//19oct05.002cc_he_1comp_hanle.pikaia.sav./ps//19oct05.002cc_he_1comp_hanle.pikaia.sav.eps

3010828x [Mm]

60
1083050
10832
Wavelength [Å]
40

−0.2

0.1
20%

1000.0150.410500.2

54

1.0

20.8

00.6

U−0.1

0−0.2300.4250.2

20V/IC

150

0502010826

%

Q/IC

weight Q−0.4y [arcsec]

0150150Q

0.00.000−0.001

0.015

weight V015050

30

V/IC

200.00.001

100.6

0150

0.002

−0.002

300

0.2

25

5

10000.8

0.215540030−20.4−40.2%

150

120

1.0

U/IC

0U/IC

150

50

−0.0010016000100 G
B=100inc=600-120°incl + azi

0.0000−0.0005500

weight U0y [Mm]30

500.0005

151001518000

0.4incl. angle γ [°]lines: azimuth. angle

0.00102015150

1500I

20000

200

LOS−velocity [km/s]

Q/IC

0150

−0.0004−0.0006

150505B

B−strength [G]15000.0002−0.0002503000.0004

101022000

0.0

atm_archive/atm_19oct05.002cc_he_1comp_hanle/input.ipt

0.0000150.2

15intensity

I0.4

19oct05.002cc, avg.fit=2.13

1520

weight I

I0.6

5000

2024000
25

10000

0.0006

Lagg et al [in prep.]
26000

Canopy Profile−0.2
105−60.010834

0.01500V−0.4−0.62040x [arcsec]

6080

Conclusions He I 10830 Å spectropolarimetry reveals a richvariety of magnetic and dynamic phenomenain the upper chromosphere.
 He I measurements complement the SOT dataand provide an important connection between
the SOT and the coronal instruments onboard
Solar B.
 MPS can provide ground-based observational
support for SOT MPS has inversion software for He I
measurements.
MPS inversion codes ...

MPS inversion codes

A. Lagg, S.K. Solanki,
Max Planck Institute for Solar System Research

MPS inversion codes Milne-Eddington inversion
 Makes use of genetic algorithm Pikaia
 Often applied to determining the magnetic field inthe upper atmosphere (He I 10830 Å) (see talk on He)
 Inversion returning depth dependentquantities (based on response functions) Similar to SIR code in many ways, but with somedifferences in philosophy
 Uses Levenberg-Marquard method for inversion

INVERT / SPINOR
 Employs response functions in order to get depth

dependent information on the atmospheric structure Radiative transfer in LTE (extension to NLTE
implemented but not sufficiently tested) Inverts also molecular lines including the molecular
Zeeman and Paschen-Back effects in Hund’s cases(a), (b) and all intermediate cases
 No constraints on types of Zeeman splitting,abundances, stellar parameters, range of
wavelengths over which lines are observed, etc.
 Philosophy: make code as versatile as possible, inorder to allow as many different solar and stellar
situations as possible to be tackled.

Versatility: Examples of types ofmodels implemented
 Plane-parallel, 1-component models to obtain averaged

properties of the atmosphere Multiple components (e.g. to take care of scattered light, or
unresolved features on the Sun). Allows for arbitrary numberof magnetic or field-free components (turns out to beimportant, e.g. in flare observations, where we have seen 4-5components).
 Flux-tubes in total pressure equilibrium with surroundings, atarbitrary inclination
 in field-free (or weak-field surroundings)
 embedded in strong fields (e.g. sunspot penumbra, or umbral dots)
 includes the presence of multiple flux tubes along a ray when

computing away from disk centre efficient computation of lines across jumps in atmospheric quantities
 Integration over solar or stellar disk, including solar/stellar

rotation

Example:penumbral flux tube
•1 tube ray (discontinuity at boundary)•1 surrounding ray
Æ confirms uncombed modelÆ flux tube thickness 100-300 km
Borrero et al.
[2006]Example:
multi ray flux tube
• multiple rays
Æ pressure balanceÆ broadening of flux tube
Frutiger [2000]

Example:
2-comp model sunspot• magnetic component:Æ height dependent
atmospheric parameters• field free comp:Æ describes stray-light

Mathew et al. [2003]

Versatility: Ease of use
 All atomic, atmospheric, parameter data are stored inseparate files: changes can be made easily
 Very easy to impose or remove constraints (e.g. massconservation along LOS or within, e.g., a convectiveelement) Very easy to add or remove free parameters, to couple
parameters between different spectral lines, or different
atmospheric components
 Very easy to give different weights to different Stokes
parameters, spectral lines, wavelength ranges, etc. Default
mode: Weights given according to error bars
 Code is written modularly: Straightforward to implement newtypes of models, if needed.