1. Science drivers for wavelength selection: Quiet Sun and Active regions Hardi Peter Kiepenheuer-Institut Freiburg, Germany Contribution to the discussions at the EUS meeting / Feb 2006

2. 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……….

3. 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

4. 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

5. Photosphere  Chromosphere Wedemeyer-Böhm et al. (2004, 2006) (M)HD models including convection photosphere and chromosphere photosphere: vis. continua & line profiles chromosphere: VUV continua vis. continuum: 5000 Å VUV continuum: 1600 Å Steiner et al. (1997) ApJ 495, 468 "old" 2D flux tube 3D MHD:

6. Chromosphere  corona side views top view  fine structured loops – highly dynamic  small loops connecting to “quiet regions”  cool plasma flows – “plasma injection” Diagnostics: VUV spectral profiles formed at logT ~ 4.5…6.5 Peter, Gudiksen & Nordlund (2006) ApJ 638, 1086

7. The whole thing: convection  corona 3D model from the convection zone to the chromosphere 5.5 x 5.5 x 3 Mm (grid: 140x140x200)  x =  y = 40 km  z = 50...12 km vertical cut: 5.5 x 3 Mm coronal emission line from 3D MHD model 60 x 60 x 34 Mm (grid: 150 3 )  x =  y = 400 km  z = 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

8. The future: convection  corona At time when Solar Orbiter will operate: 3D models accounting for complex interaction of photosphere – chromosphere – TR– corona system on AR / supergranular scale Observations needed to account for all atmospheric regimes !! Carlsson & Hansteen (2005) ESA SP-596, 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 vertical velocity  =1 line

9. 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

10. vertical z [ Mm] current log 10 J 2 mean B 2 mean J 2 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! Gudiksen & Nordlund (2002) ApJ 572, L113 Aschwanden (2001)

11. Where things do happen: temporal variability  large variability in TR  smooth variation in coronal intensity  variability in coronal shift comparable to TR !!  similar variations found in observations! A real observation: SUMER / SOHO S IV (1394 Å) ~ 10 5 K 1x1’’, 10 sec exposures highest dynamics in transition region Peter, Gudiksen & Nordlund (2005) ESA SP-592

12. Coronal heating and TR explosive events Si IV (1393 Å) ~10 5 K ~10 min 200 km/s ~25’’ SUMER solar 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

13. Propagation from chromosphere into corona 10 6 4 2 0 8 20 40 60 80 100 position along the slit [arcsec] time [10 3 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: Int 3 min continuous information from chromosphere  TR is needed

14. Doppler shifts in the low corona & TR Peter & Judge (1999) ApJ 522, 1148 mean quiet Sun Doppler shifts at disk center  net redshift in transition region  net blueshift in corona  in active region similar but with higher amplitude SUMER need for high spectral resolution  > 30 000 to get 1 km/s

15. 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 10 6 K  to study source of solar wind: investigate "cool" corona Tu, Zhou, Marsch et al. (2005) Sci 308, 519 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 of solar wind source

16. Response of the atmosphere to energetic events Yohkoh SXT TRACE 195A SUMER slit Si III 0.05 MK Ca X 0.7 MK Ne VI 0.3 MK Fe XIX 6.3 MK Fe XIX line shift Fe XVII 2.8 MK Ca XIII 2.0 MK Ca X 0.7 MK Fe XIX 6.3 MK follow dynamic cooling phase of an energetic event e.g. SUMER: 1100 – 1140 Å spanning log T = 4.7 … 6.8 cover large temperature interval to study response to energetic events Coronal loop oscillations Curdt et al. (2005) ESA SP 592, 475 time space 1112 – 1120 Å

17. 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

18. EUI  Photosphereimaging vis. / G-band IR + vis spectropolarimetry: vector B  ChromosphereCa II H + K / H  He I (10830 Å) vector B EUV continua ~1000 – 1600 Å  transition regionemission line spectra VUV Dopplergrams for C IV (VUV-FPI ?)  coronaemission line spectra VUV / EUV imaging [ logT = 4…6.5 ] X-ray imaging [ logT > 6 ] Diagnostics through the atmosphere EUS VIM

19. "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

20. 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<10 6 K – to get acceleration: T=10 5 …10 6 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 good spectral resolution: e.g. 1 km/s = Ne VIII 770 Å : 10 mÅ Fe IX 171 Å : 2 mÅ only >912 Å allows to reach temperature minimum e.g.: Mg X 609 / 625 Å Ne VIII 770 / 780 Å N V 1239 / 1243 Å C III 977 / 1175 Å v < 5 km/s only then loop flows, CH outflow and profile details e.g. for explosive events

21. A well suited band proposed by Teriaca, Schühle & Curdt for =1163–1266 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 )

22. 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.

23. not to be used…

24.  3D MHD model for the corona: 50 x 50 x 30 Mm Box ( 150 3 ) – 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  j 2 ~ exp(- z/H )  loop-structured 10 6 K corona Gudiksen & Nordlund (2002) ApJ 572, L113 (2005) ApJ 618, 1020 & 1031 Bingert, Peter, Gudiksen & Nordlund (2005) 3D MHD coronal modeling horizontal x [ Mm] horizontal y [ Mm] MDI magnetogram vertical z [ Mm] current log 10 J 2 mean B 2 mean J 2 histogram of currents 010 20 3040 10 20 horizontal X [Mm] vertical Z [Mm] Bingert et al. (2005) “emission” @ 10 6 K

25. total ionization  0.8 abundance = const. ionization excitation 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 n e ) log T [K] normalized contribution emissivity in the computational box as a function of T From the MHD model: – density  (fully ionized)  n e at each – temperature  T grid point and time Emissivity from a 3D coronal model Emissivity at each grid point and time step:  f (T)

26. DEM inversion using CHIANTI: 1 – using synthetic spectra derived from 3D MHD model 2 – using solar observations (SUMER, same lines) Emission measure Si II Mg X Supporting suggestions that numerous cool structures cause increase of DEM to low T 1D loop model – flat good match to observations!! DEM increases towards low T in the model !

27. The whole thing: convection  corona: a problem 3D model from the convection zone to the chromosphere 5.5 x 5.5 x 3 Mm (grid: 140x140x200)  x =  y = 40 km  z = 50...12 km vertical cut: 5.5 x 3 Mm coronal emission line from 3D MHD model 60 x 60 x 34 Mm (grid: 150 3 )  x =  y = 400 km  z = 400...150 km vertical cut: 60 x 34 Mm 2 4 6 8 10 12 14 16 temperature [ 1000 K ] Wedemeyer et al. (2004) A&A 414, 1121  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