SECCHI3 D reconstruction software Wiegelmann Inhester Feng Ruan

SECCHI-3 D reconstruction software Wiegelmann, Inhester, Feng, Ruan, Thalmann, Podlipnik • • • Tools to compute coronal magnetic fields Selfconsistent magnetohydrostatic equilibria Feature recognition Stereoscopy Tomography Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Aim: 3 D Reconstruction of Solar Corona • The 2 Viewpoints of STEREO help us for a 3 D-reconstruction. • But: Image data are not sufficient (see talk of Feng) • Essential: Magnetic field information. • Our tools use combined data sets of SECCHI with photospheric B-field measurements from various instruments (SOHO, HINODE, SOLIS) Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Coronal magnetic field codes • Potential, linear and nonlinear force-free extrapolation codes -Cartesian (Active Regions) and -Spherical (Full Sun) geometry • Selfconsistent magnetohydrostatic codes: B-field + Plasma in one MHS-model -Cartesian -Spherical Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Model Mathematics Potential Fields Linear Force. Free Fields Non Linear Force-Free MHS Equilibrium Orsay, 07. 03. 2007 Observations Validity needed Line of sight magnetogram (Global) current free regions, quiet sun LOS magnetogram + observations of plasma structures Local in active regions, low-beta plasma Better Models More Challenging Computational + Observational Vectormagnetogram Active regions, (3 times more data, low beta plasma in low corona ambiguities, noise) Vectormagnetogram Helmet streamer, finite beta plasma, + Tomographic Inversion of density full solar corona 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Easy to compute Require only LOS-Magnetograms Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Very Challenging Vector-Magnetograms Pre-processing Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Comparison of observed magnetic loops and extrapolations from photospheric measurements (Wiegelmann et al. , A&A 2005) Nonlinear force-free Models are superior. Measured loops in a newly developed AR (Solanki et al. , Nature 2003) Linear force-free reconstruction Orsay, 07. 03. 2007 Potential field reconstruction Non-linear force-free reconstruction 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

What do coronal B-field models provide? • • 3 D loop structure +projections on 2 images Length + shape of loops Magnetic field strength Electric current density (Free) magnetic energy Helicity Orsay, 07. 03. 2007 Stereoscopy Scaling Laws CME-onset 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

What does SECCHI provide? • • Rigorous Test of B-field models. Compare real + artificial images, Obtain free model parameters. Loops + B-lines Test scaling laws. Get plasma parameters along loops - Temperature Modeling, - Density Tomography - Pressure • Compare selfconsistent MHS-models with coronagraph images (Talk of Ruan) Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Single viewpoint: SOHO/EIT, TRACE Use B-Field for feature-recognition (Wiegelmann et al. , Sol. Phys. 2005) • • Compute the coronal magnetic field. Project 3 D field lines onto an EUV-image. Emissivity and gradient along projected field lines. Compare field lines and plasma. How well are they aligned? • Alternative: Extract 1 -D loops out of the EUV-images (see talk of Inhester) and compare with projections of magnetic field lines thereafter. Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

We use a linear force-free model with MDI-data and have the freedom to choose an appropriate value for the force-free parameter α. EIT-image and projections of magnetic field lines for a potential field (α=0). (bad agreement) Orsay, 07. 03. 2007 Linear force-free field with α=+0. 01 [Mm-1] (bad agreement) 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Linear force-free field with α=-0. 01 [Mm-1] (better agreement) Orsay, 07. 03. 2007 3 D-magnetic field lines, linear force-free α=-0. 01 [Mm-1] 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

down 3 D-Loops guide Data Analysis SUMER Dopplergram in Ne. VIII ( 77 nm) and a 2 -D-projection of some field lines. (Marsch, Wiegelmann, Xia, A&A 2004) Orsay, 07. 03. 2007 up Mass flux density inferred from Dopplershift and intensity from SUMER observations 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

What does the method provide? • Rates quality of magnetic field reconstruction. • Identifies coronal loops. • For a linear force-free model the method computes the optimal force-free parameter α. • The method tells us also how good the assumption “linear force-free” is. (This assumption is good if the optimal value α is the same on all loops. ) • Two viewpoints will be more restrictive. Magnetic Stereoscopy, Talk of Feng Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Magnetic fields and coronal tomography a) Use only line of sight density integrals. b) Use only magnetic field data. Magnetic Models support Tomography, Regularization c) Use both line of sight density integrals and magnetic field as regularization operator. Wiegelmann and Inhester, Sol. Phys, 2003 Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Summary • We developed tools for the 3 D-reconstruction of the solar corona (global and local). • Combined data-analysis of SECCHI-data with magnetic field information are more powerful than 2 STEREO-viewpoints alone. • It is fortunate that we have STEREO and HINODE data available at the same time. SECCHI + HINODE + Reconstruction Tools = Corona in 3 D Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

References (Selection) Coronal magnetic field models T. Wiegelmann: Optimization code with weighting function for the reconstruction of coronal magnetic fields. (Sol. Phys. , Vol. 219: 87 -108, 2004. ) T. Wiegelmann, A. Lagg, S. K. Solanki, B. Inhester, J. Woch: Comparing magnetic field extrapolations with measurements of magnetic loops. (A&A, Vol. 433, 701 -705, 2005. ) T. Wiegelmann, B. Inhester, T. Sakurai: Preprocessing of vector magnetograph data for a nonlinear force-free magnetic field reconstruction. (Sol. Phys, Vol. 233, 215 -232, 2006. ) B. Inhester and T. Wiegelmann : Nonlinear force-free magnetic field extrapolations: comparison of the Grad-Rubin and Wheatland-Sturrock-Roumeliotis algorithm. (Sol. Phys. , Vol. 235, 201 -221, 2006) T. Wiegelmann and T. Neukirch: An optimization principle for the computation of MHD equilibria in the solar corona. (A&A, Vol. 457, 1053 -1058, 2006. ) T. Wiegelmann: Computing nonlinear force-free coronal magnetic fields in spherical geometry. (Solar Physics, in press, 2007) Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software

Stereoscopy T. Wiegelmann and T. Neukirch: Including Stereoscopic Information in the Reconstruction of Coronal Magnetic Fields. (Sol. Phys. , Vol. 208: 233 -251, 2002. ) T. Wiegelmann and B. Inhester: Magnetic Stereoscopy. (Solar Physics, Vol. 236, 25 -40, 2006. ) L. Feng, T. Wiegelmann, B. Inhester, S. K. Solanki, W. Q. Gan, P. Ruan : Magnetic Stereoscopy of Coronal Loops in NOAA 8891. (Sol. Phys. , accepted. ) B. Inhester: Stereoscopy Basics for the Stereo mission (ISSI publication, submitted. ) Tomography T. Wiegelmann and B. Inhester: Magnetic modeling and tomography: First steps towards a consistent reconstruction of the solar corona. (Solar Physics, Vol. 214: 287 -312, 2003. ) Feature recognition T. Wiegelmann, B. Inhester, A. Lagg, S. K. Solanki: How to use magnetic field information for coronal loop identification? (Sol. Phys. , Vol. 228, 67 -78, 2005. ) Orsay, 07. 03. 2007 5 th SECCHI Consortium Meeting: Wiegelmann et al. : SECCHI-3 D reconstruction software