Science drivers for wavelength selection Quiet Sun and

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

Unique scientific goals of Solar Orbiter Ø Determine the properties, dynamics and interactions of plasma, fields and particles in the near-Sun heliosphere Ø Investigate the links between the solar surface, corona and inner heliosphere Ø Explore, at all latitudes, the energetics, dynamics and fine-scale structure of the Sun's magnetized atmosphere Ø Probe the solar dynamo by observing the Sun's high-latitude field, flows and seismic waves cited from the 1 st announcement for the 2 nd 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 Ø 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 Ø 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 Ø consequences – – diagnostics through the atmosphere interaction of orbiter instruments diagnostic needs a well suited band

Energy source: photospheric magneto-convection 3 D 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 Vögler, Shelyag, Schüssler et al. (2005) A&A 429, 335

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

Chromosphere °corona Ø fine structured loops – highly dynamic Diagnostics: Ø small loops connecting to “quiet regions” VUV spectral profiles formed at log. T ~ 4. 5… 6. 5 top view side views Peter, Gudiksen & Nordlund (2006) Ap. J 638, 1086 Ø cool plasma flows – “plasma injection”

The whole thing: convection ° coronal emission line from 3 D MHD model 60 x 34 Mm (grid: 1503) Dx = Dy = 400 km Dz = 400. . . 150 km vertical cut: 60 x 34 Mm 3 D model from the convection zone to the chromosphere Ø modeling the full system will not be possible very soon (box size > 1500 x 500) Ø two step process: convection zone – photosphere – chromosphere – corona Ø but in time: large models from convection °corona 5. 5 x 3 Mm (grid: 140 x 200) Dx = Dy = 40 km Dz = 50. . . 12 km vertical cut: 5. 5 x 3 Mm

The future: convection °corona 2 D model convection °corona Ø photospheric flows/fields and coronal temperature look as being disconnected Carlsson & Hansteen (2005) ESA SP-596, 261 Ø one needs information from chromosphere and TR to be able to understand the connection and interaction of photosphere and corona At time when Solar Orbiter will operate: 3 D models accounting for complex interaction of photosphere – chromosphere – TR– corona system on AR / supergranular scale coronal temperature b=1 line vertical velocity Observations needed to account for all atmospheric regimes !!

Outline Ø 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 Ø 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 Ø consequences – – diagnostics through the atmosphere interaction of orbiter instruments diagnostic needs a well suited band

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 histogram of currents mean B 2 log 10 J 2 mean J 2 vertical z [ Mm] investigate TR temperatures! Aschwanden (2001) current Gudiksen & Nordlund (2002) Ap. J 572, L 113 – dissipation in 3 D MHD coronal models

Coronal heating and TR explosive events Ø transient broadening of TR emission lines, sometimes distinct emission peaks visible (e. g. Dere et al. , 1989, Sol. Phys. 123, 41) Ø interpreted as bi-directional jets after reconnection (e. g. Innes et al. , 1997, Nat. 386, 811) Ø explosive events are restricted to TR temperatures Ø how are they related to the dissipation of energy in the 3 D MHD flux-braiding coronal models? high spatial & spectral resolution TR line profiles needed ~105 K ~10 min solar Y ~25’’ Si IV (1393 Å) l 200 km/s from a time series 28. 3. 1996 ~1 min cadence (originally ~10 s) SUMER

Propagation from chromosphere into corona Ø oscillations are present in line shift and intensity Ø 5 -10 m. Hz oscillations can be followed up from the chromosphere into the transition region 10 time [103 sec] 8 C II: shift continuum 3 min continuous information from chromosphere °TR is needed O VI: Int 6 4 2 C II: shift continuum 0 20 40 60 80 100 position along the slit [arcsec] Wikstøl et al. (2000) Ap. J 531, 1150

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

Source and acceleration of solar wind outflow coronal holes as the source of the fast wind never reach 106 K ° to study source of solar wind: investigate "cool" corona 0. 9 MK electron temperature: model: ––––––(Hackenberg et al. 2000) Tu, Zhou, Marsch et al. (2005) Sci 308, 519 observations: (Wilhelm et al. 1998) diagnostics of solar wind source Ne VIII (770 Å) C IV (1548 Å) Si II (1533 Å) continuum need for Doppler shifts & widths through TR and low corona: <0. 9 MK

Response of the atmosphere to energetic events Coronal loop oscillations follow dynamic cooling phase of an energetic event Fe XIX line shift SUMER slit e. g. SUMER: 1100 – 1140 Å spanning log T = 4. 7 … 6. 8 Fe XIX 6. 3 MK Yohkoh SXT Ca XIII 2. 0 MK 1112 – 1120 Å Ca X 0. 7 MK Si III 0. 05 MK Ca X 0. 7 MK TRACE 195 A Ne VI Fe XIX 0. 3 MK 6. 3 MK time Curdt et al. (2005) ESA SP 592, 475 cover large temperature interval to study response to energetic events space Fe XVII 2. 8 MK

Outline Ø 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 Ø 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 Ø consequences – – diagnostics through the atmosphere interaction of orbiter instruments diagnostic needs a well suited band

Diagnostics through the atmosphere Ø Photosphere imaging vis. / G-band IR + vis spectropolarimetry: vector B Ø Chromosphere VIM Ca II H + K / Ha He I (10830 Å) vector B EUV continua ~1000 – 1600 Å Ø transition region emission line spectra VUV Dopplergrams for C IV (VUV-FPI ? ) Ø corona EUS emission line spectra VUV / EUV imaging [ log. T = 4… 6. 5 ] X-ray imaging [ log. T > 6 ] EUI

"Interaction" of orbiter instruments VIM – photospheric vector magnetic fields Ø provides photospheric flows and vector magnetic fields Ø will be specially designed also to be able to provide reliable magnetic field information suited for coronal field extrapolation Ø huge efforts for reliable extrapolations, e. g. at MPS Lindau EUI – chromospheric °coronal imaging Ø provides VUV images: log. T = ~4 Ø provides EUV images: log. T = >6 (Lya ? ) (171 Å? ) EUS Ø should cover parts of the solar atmosphere also accessible to the other instruments Ø close the gap in the atmosphere, the imaging instruments cannot cover Ø provide information on flows and densities where other instruments operate

Diagnostic needs Ø interaction chromosphere – corona – chromospheric continua ( > 912 Å / Ly–edge ) Ø chromosphere – TR – corona system – propagation of waves – plasma properties through atmosphere: line shifts, widths Ø dissipation of energy to heat corona – TR dynamics and explosive events: spectral profiles – chromospheric and coronal response Ø coronal holes at high latitudes: source of solar wind – in coronal holes: T<106 K v < 5 km/s – to get acceleration: T=105… 106 K Ø energetic events – cover large temperature range Ø good spectral resolution: l/Dl > 30 000 – line profile details and Doppler shifts down to 1 km/s only l>912 Å allows to reach temperature minimum 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 e. g. : Mg X 609 / 625 Å Ne VIII 770 / 780 Å N V 1239 / 1243 Å C III 977 / 1175 Å only then loop flows, CH outflow and profile details e. g. for explosive events

Problematic: no good "solar wind lines" T < 0. 9 MK (e. g. Ne VIII) proposed by Teriaca, Schühle & Curdt for l=1163– 1266 Å A well suited band this band nicely covers: – low chromosphere (continuum "for free") – chromosphere – transition region – low corona (coronal holes) – hot corona (flares)

Conclusions Ø Solar Orbiter provides unique opportunity to study the complex interactions of the photosphere – chromosphere – TR – corona – heliosphere system Ø in order to ideally complement the other instruments (EUI/VIM) EUS has to cover the chromosphere – TR – corona system Ø it is not sufficient to cover only hot temperature plasma: models need information also on chromosphere – TR system Ø 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.

not to be used…

3 D MHD coronal modeling Ø starting with scaled-down MDI magnetogram – no emerging flux Ø photospheric driver: foot-point shuffled by convection Ø braiding of magnetic fields (Galsgaard, Nordlund 1995; JGR 101, 13445) âheating: DC current dissipation (Parker 1972; Ap. J 174, 499) currents mean B 2 10 0 2 MDI 20 10 magnetogram 30 mean J 40 horizontal X [Mm] vertical z [ Mm] âheating rate h j 2 ~ exp(- z/H ) âloop-structured 106 K corona horizontal x [ Mm] Bingert et al. (2005) (heat conduction, rad. losses) 20 “emission” @ 106 K histogram of horizontal y [ Mm] Ø full energy equation Gudiksen & Nordlund (2002) Ap. J 572, L 113 (2005) Ap. J 618, 1020 & 1031 Bingert, Peter, Gudiksen & Nordlund (2005) current vertical log 10 JZ 2 [Mm] Ø 3 D MHD model for the corona: 50 x 30 Mm Box (1503) – fully compressible; high order – non-uniform mesh

Emissivity from a 3 D coronal model From the MHD model: – density r (fully ionized) ne – temperature T at each grid point and time Emissivity at each grid point and time step: normalized contribution emissivity in the computational box as a function of T total ionization » 0. 8 abundance = const. ionization » f (T) excitation Assumptions: – equilibrium excitation and ionisation (not too bad. . . ) – photospheric abundances use CHIANTI to evaluate ratios log T [K] (Dere et al. 1997) G depends mainly on T (and weakly on ne)

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

The whole thing: convection ° corona: a problem coronal emission line from 3 D MHD model 60 x 34 Mm (grid: 1503) Dx = Dy = 400 km Dz = 400. . . 150 km vertical cut: 60 x 34 Mm 4 Wedemeyer et al. (2004) A&A 414, 1121 6 Ø modeling the full system will not be possible very soon (box size > 1500 x 500) Ø two step process: convection zone – photosphere – chromosphere – corona Ø but in time: large models from convection °corona 8 10 12 14 16 temperature [ 1000 K ] 2 3 D model from the convection zone to the chromosphere 5. 5 x 3 Mm (grid: 140 x 200) Dx = Dy = 40 km Dz = 50. . . 12 km vertical cut: 5. 5 x 3 Mm