Science driversfor wavelength selection:
Quiet Sun and Active regions
Hardi Peter
Kiepenheuer-Institut
Freiburg, GermanyContribution to the discussionsat the EUS meeting / Feb 2006
Unique scientific goals of Solar Orbiter
Determine the properties, dynamics and interactions of plasma, fields and particles in the near-Sun heliosphere
Investigate the links between the solar surface, corona and inner heliosphere
Explore, at all latitudes, the energetics, dynamics and fine-scale structure of the Sun's magnetized atmosphere
Probe the solar dynamo by observing the Sun's high-latitude field, flows and seismic waves
cited from the 1st announcement for the 2nd Orbiter Workshop, Oct 2006
cover the whole atmosphere
from the photosphere, chromosphere, TR into the corona
we will get data not much before 2020……….
Outline state of the art models of the solar atmosphere: connecting the convection zone to the corona
– magneto-convection in the photosphere – chromospheric models – coronal models – the future: the whole atmosphere in one model
selection of special problems:
– where does coronal heating occur? – temporal variability – coronal heating and small-scale transients – wave propagation from the chromosphere into corona – Doppler shifts – source of the solar wind – response to energetic events
consequences
– diagnostics through the atmosphere – interaction of orbiter instruments – diagnostic needs – a well suited band
Energy source: photospheric magneto-convection
Vögler, Shelyag, Schüssler et al. (2005) A&A 429, 335
3D MHD model of magneto-convection:
Diagnostics: – vis. continuum (white light) – magnetic field (vis. & IR Zeeman)
G-Band observations
Rouppe van der Voort et al. (2006) A&A 435, 327
Photosphere ChromosphereW
edem
eyer
-Böh
m e
t al
. (2
004
, 2
006)
(M)HD models including convectionphotosphere and chromosphere
photosphere: vis. continua & line profiles
chromosphere: VUV continua
vis. continuum: 5000 Å VUV continuum: 1600 Å
Ste
iner
et
al.
(199
7) A
pJ 4
95,
468
"old" 2D flux tube
3D MHD:
Chromosphere corona
side viewstop view
fine structured loops – highly dynamic
small loops connecting to “quiet regions”
cool plasma flows – “plasma injection”
Diagnostics:
VUV spectral profiles formedat logT ~ 4.5…6.5
Pet
er,
Gud
ikse
n &
No
rdlu
nd (
2006
) A
pJ 6
38,
108
6
The whole thing: convection corona
3D modelfrom theconvection zoneto the chromosphere
5.5 x 5.5 x 3 Mm (grid: 140x140x200)
x = y = 40 kmz = 50...12 km
vertical cut:5.5 x 3 Mm
coronal emission linefrom 3D MHD model
60 x 60 x 34 Mm (grid: 1503)
x = y = 400 kmz = 400...150 km
vertical cut:60 x 34 Mm
modeling the full system will not be possible very soon (box size 1500 x 1500 x 500) two step process: convection zone – photosphere – chromosphere chromosphere – corona but in time: large models from convection corona
The future: convection corona
At time when Solar Orbiter will operate:3D models accounting for complex interaction ofphotosphere – chromosphere – TR– corona systemon AR / supergranular scale
Observations needed to account forall atmospheric regimes !!
Car
lsso
n &
Han
stee
n (2
005)
ES
A S
P-5
96,
261
2D model convection corona
photospheric flows/fields and coronal temperature look as being disconnected
one needs information from chromosphere and TR to be able to understand the connection and interaction of photosphere and corona
coronal temperature
verticalvelocity
=1 line
Outline state of the art models of the solar atmosphere: connecting the convection zone to the corona
– magneto-convection in the photosphere – chromospheric models – coronal models – the future: the whole atmosphere in one model
selection of special problems:
– where does coronal heating occur? – temporal variability – coronal heating and small-scale transients – wave propagation from the chromosphere into corona – Doppler shifts – source of the solar wind – response to energetic events
consequences
– diagnostics through the atmosphere – interaction of orbiter instruments – diagnostic needs – a well suited band
vertical z [ Mm]
curr
ent
lo
g 10 J
2
mean B2
mean J2
histogram of currents
Where does coronal heating occur ?
in moderately active regions and quiet Sun:bulk part of the heating occurs at TR temperatures
– scale height in loop models – dissipation in 3D MHD coronal models
investigate TR temperatures!
Gud
ikse
n &
Nor
dlun
d (2
002)
ApJ
572
, L1
13
Asc
hwan
den
(200
1)
Coronal heating and TR explosive events
Si IV (1393 Å) ~105 K ~10 min
200 km/s
~25
’’
SUMER
sola
r Y
from a time series 28.3.1996~1 min cadence (originally ~10 s)
transient broadening of TR emission lines, sometimes distinct emission peaks visible (e.g. Dere et al.,1989, Sol. Phys. 123, 41)
interpreted as bi-directional jets after reconnection (e.g. Innes et al., 1997, Nat. 386, 811)
explosive events are restricted to TR temperatures
how are they related to the dissipation of energy in the 3D MHD flux-braiding coronal models?
high spatial & spectral resolution TR line profiles needed
Propagation from chromosphere into corona
10
6
4
2
0
8
20 40 60 80 100position along the slit [arcsec]
time
[103
sec]
continuum C II: shift O VI: Int
Wikstøl et al. (2000) ApJ 531,1150
oscillations are present in line shift and intensity 5-10 mHz oscillations can be followed up from the chromosphere into the transition region
continuum
C II: shift
O VI: Int3 min
continuous informationfrom chromosphere TRis needed
Doppler shifts in the low corona & TRP
eter
& J
udge
(19
99)
ApJ
52
2, 1
148
mean quiet SunDoppler shiftsat disk center
net redshift in transition region
net blueshift in corona
in active region similar but with higher amplitude
SUMER
need for highspectral resolution > 30 000to get 1 km/s
Source and acceleration of solar wind outflow
need for Doppler shifts & widths through TR and low corona: <0.9 MK
coronal holes as the source
of the fast wind never reach 106 K
to study source of solar wind: investigate "cool" corona
Tu,
Zho
u, M
arsc
h et
al.
(20
05)
Sci
308
, 51
9
electron temperature:
model: ––––––––––––- (Hackenberg et al. 2000)
observations: (Wilhelm et al.1998)
0.9 MK
Ne VIII (770 Å)
C IV (1548 Å)
Si II (1533 Å)continuum
diagnostics ofsolar wind source
Response of the atmosphere to energetic events
YohkohSXT
TRACE 195A
SUMER slit
Si III0.05 MK
Ca X0.7 MK
Ne VI0.3 MK
Fe XIX6.3 MK
Fe XIXline shift
Fe XVII2.8 MK
Ca XIII2.0 MK
Ca X0.7 MK
Fe XIX6.3 MK
follow dynamiccooling phaseof an energetic event
e.g. SUMER: 1100 – 1140 Å
spanning log T = 4.7 … 6.8
cover large temperature intervalto study response to energetic events
Coronal loop oscillations
Cur
dt e
t al
. (2
005)
ES
A S
P 5
92,
475
time
spac
e
1112 – 1120 Å
Outline state of the art models of the solar atmosphere: connecting the convection zone to the corona
– magneto-convection in the photosphere – chromospheric models – coronal models – the future: the whole atmosphere in one model
selection of special problems:
– where does coronal heating occur? – temporal variability – coronal heating and small-scale transients – wave propagation from the chromosphere into corona – Doppler shifts – source of the solar wind – response to energetic events
consequences
– diagnostics through the atmosphere – interaction of orbiter instruments – diagnostic needs – a well suited band
EUI
Photosphere imaging vis. / G-band
IR + vis spectropolarimetry: vector B
Chromosphere Ca II H + K / H
He I (10830 Å) vector B
EUV continua ~1000 – 1600 Å
transition region emission line spectra
VUV Dopplergrams for C IV (VUV-FPI ?)
corona emission line spectra
VUV / EUV imaging [ logT = 4…6.5 ]
X-ray imaging [ logT > 6 ]
Diagnostics through the atmosphere
EUS
VIM
"Interaction" of orbiter instruments
VIM – photospheric vector magnetic fields
provides photospheric flows and vector magnetic fields will be specially designed also to be able to provide
reliable magnetic field information suited for coronal field extrapolation huge efforts for reliable extrapolations, e.g. at MPS Lindau
EUI – chromospheric coronal imaging
provides VUV images: logT = ~4 (Ly ?) provides EUV images: logT = >6 (171 Å?)
EUS
should cover parts of the solar atmosphere also
accessible to the other instruments
close the gap in the atmosphere, the imaging instruments cannot cover
provide information on flows and densities where other instruments operate
Diagnostic needs interaction chromosphere – corona
– chromospheric continua ( > 912 Å / Ly–edge )
chromosphere – TR – corona system
– propagation of waves – plasma properties through atmosphere: line shifts, widths
dissipation of energy to heat corona
– TR dynamics and explosive events: spectral profiles – chromospheric and coronal response
coronal holes at high latitudes: source of solar wind
– in coronal holes: T<106 K – to get acceleration: T=105…106 K
energetic events
– cover large temperature range
good spectral resolution: > 30 000
– line profile details and Doppler shifts down to 1 km/s
longer wavelengths:"easier" to get goodspectral resolution:e.g. 1 km/s =Ne VIII 770 Å : 10 mÅ Fe IX 171 Å : 2 mÅ
only >912 Åallows to reachtemperature minimum
e.g.:Mg X 609 / 625 Å Ne VIII 770 / 780 ÅN V 1239 / 1243 ÅC III 977 / 1175 Å
v < 5 km/s
only then loop flows,CH outflow andprofile details e.g. forexplosive events
A well suited band
prop
osed
by
Ter
iaca
, S
chüh
le &
Cur
dtfo
r =
1163
–126
6 Å
this band nicely covers:
– low chromosphere (continuum "for free")
– chromosphere
– transition region
– low corona (coronal holes)
– hot corona (flares)
Problematic:no good "solar wind lines"
T < 0.9 MK (e.g. Ne VIII)
Conclusions
Solar Orbiter provides
unique opportunity to study the complex interactions of the
photosphere – chromosphere – TR – corona – heliosphere system
in order to ideally complement the other instruments (EUI/VIM)
EUS has to cover the chromosphere – TR – corona system
it is not sufficient to cover only hot temperature plasma:
models need information also on chromosphere – TR system
if one misses out the chromosphere – TR system,
there will be a serious ambiguity in checking future models
for the dynamics and heating of the corona
Thanks for replacing the LAMP.
3D MHD model for the corona: 50 x 50 x 30 Mm Box (1503) – fully compressible; high order – non-uniform mesh
full energy equation (heat conduction, rad. losses)
starting with scaled-down MDI magnetogram – no emerging flux
photospheric driver: foot-point shuffled by convection
braiding of magnetic fields (Galsgaard, Nordlund 1995; JGR 101, 13445)
heating: DC current dissipation (Parker 1972; ApJ 174, 499)
heating rate j2 ~ exp(- z/H )
loop-structured 106K corona
Gudiksen & Nordlund (2002) ApJ 572, L113 (2005) ApJ 618, 1020 & 1031Bingert, Peter, Gudiksen & Nordlund (2005)
3D MHD coronal modeling
horizontal x [ Mm]
ho
rizo
nta
l
y [
Mm
]
MDI magnetogram
vertical z [ Mm]
curr
ent
lo
g 10 J
2
mean B2
mean J2
histogram of currents
0 10 20 30 40
10
20
horizontal X [Mm]
ve
rtic
al
Z
[Mm
]
Bin
ger
t et
al.
(200
5)“emission” @ 106 K
21e ),( AhnTG ione
2
nn
n
el
ion
n
n
e
H
n
n
H
el
n
n
3m
W
total ionization 0.8
abundance = const.
ionizationexcitation
Assumptions:– equilibrium excitation and ionisation (not too bad...)
– photospheric abundances
use CHIANTI to evaluate ratios (Dere et al. 1997) G depends mainly on T (and weakly on ne) log T [K]
norm
aliz
ed c
ontr
ibut
ion
emissivity in the computational box as a function of T
From the MHD model: – density (fully ionized) ne at each
– temperature T grid point and time
Emissivity from a 3D coronal model
Emissivity at each grid point and time step:
f (T)
DEM inversion using CHIANTI:
1 – using synthetic spectra derived from 3D MHD model
2 – using solar observations (SUMER, same lines)
Emission measure
T
hnDEM
d
d2e
Si II Mg X
Supporting suggestions thatnumerous cool structures
cause increase of DEM to low T
1D loop model – flatgood match to observations!!DEM increases towards low T in the model !
The whole thing: convection corona: a problem
3D modelfrom theconvection zoneto the chromosphere
5.5 x 5.5 x 3 Mm (grid: 140x140x200)
x = y = 40 kmz = 50...12 km
vertical cut:5.5 x 3 Mm
coronal emission linefrom 3D MHD model
60 x 60 x 34 Mm (grid: 1503)
x = y = 400 kmz = 400...150 km
vertical cut:60 x 34 Mm
2
4
6
8
10
12
14
16
tem
pera
ture
[
100
0 K
]
Wed
emey
er e
t al
. (2
004)
A&
A 4
14,
11
21
modeling the full system will not be possible very soon (box size 1500 x 1500 x 500) two step process: convection zone – photosphere – chromosphere chromosphere – corona but in time: large models from convection corona