Magnetic Stereoscopy of the Coronal Loops L.Feng, T.Wiegelmann, B.Inhester, S.Solanki, P.Ruan Max-Planck Institute for Solar System Research

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  • Magnetic Stereoscopy of the Coronal LoopsL.Feng, T.Wiegelmann, B.Inhester, S.Solanki, P.Ruan Max-Planck Institute for Solar System Research

    Feng et al.

  • Task: 3D loop geometry from the two-viewpoint 2D imagesProblems in the classical stereoscopyAn application of the magnetic stereoscopy 3D reconstruction from two TRACE images with the help of the magnetic field linesA preparation tool for the EUVI image pair

    Feng et al.

  • Two-view TRACE images mimicking the EUVI image pairClassical stereoscopy: Correspondence problem: Which two loops in the two images are the projections of the same loop in the real 3D case? (difficult)Reconstruction problem: how to determine the 3D coordinates

    Feng et al.

  • Solution to the reconstruction problem of curve-like featuresIntersection of two back-projection surfaces generated from two view directions. (Inhester, 2007, submitted)

    Feng et al.

  • Reconstruction ambiguityReconstruction of east-west orientation loops has two solutions, which one is correct? Two-viewpoint images are not sufficient

    Feng et al.

  • An application of the magnetic stereoscopy3D geometry of the coronal loops in AR 8891

    Two unsolved problems in Part I1. The correspondence problem2. The ambiguity problem

    3D magnetic field lines in the corona are important

    Feng et al.

  • Description of AR 8891long-lived active region (12 days) Stereoscopy: 1-Mar-2000, 2-Mar-2000 quite, no flare happeningThe global magnetic field evolves very slowlyquasi-stationary loop structures MDI/SOHO 1-Mar-2000 1539

    Feng et al.

  • Loop identification The loops are traced by eye (subjective)The loop segmentation tool for EUVI (talk of Inhester) 1-Mar-2000, 14:222-Mar-2000, 17:44

    Feng et al.

  • 3D Magnetic field line in the coronaLinear force-free field model: is constant over the AR Input data: line-of-sight MDI magnetogram

    45 values 4183 field lines are storedan example of =0, potential field

    Feng et al.

  • footpoints: randomly selectedField line projection onto two TRACE images

    Feng et al.

  • Magnetic StereoscopyStep 1: Loop pair identification - correspondence problemStep 2: Geometrical stereoscopy reconstruction problemReconstruction materials:For viewpoint A, we have 4183 field lines and 5 loopsFor viewpoint B, we have 4183 field lines and 6 loops

    Feng et al.

  • For every loop combination: LA (Image A)- LB (ImageB) CLALB (bi) =( CLA (bi) + CLB (bi) ) / 2, CL (bi): averaged distance between L and bi

    a field line b (LA, LB) best fitted with (LA, LB) is found by CLALB = min { CLALB (bi) } , goodness of the correspondence the smaller, the better .

    Sorting CLALB Looking for loop pairs

    Feng et al.

  • random starting points in the MDI map a new refined group of field linesLoop pair (1, 1), C=3.71 Loop pair (0, 0), C=1.54 loop correspondence measure

    Feng et al.

  • Identified loop pairs - correspondence problemPossible loop pairs: the evolution of the coronal loops during a day

    loop pair 0-01-1 1-22-34-4*L-1.2-1.5-1.5-0.20.8

    Feng et al.

  • Complete loop feature identificationBest fitting field line helps find loop footpoints and trace a complete loop

    Feng et al.

  • Geometrical stereoscopysolutions: real 3D loop & ghost featuresMethod testing3D reconstruction from 2 projected field lines of b(0,0)Magnetic stereoscopyThe extent of the two surfaces is limited.ZStep2: Geometrical stereoscopyReconstruction ambiguity

    Feng et al.

  • Magnetic stereoscopy of the loop pair 0-0The loop top will be the most uncertain part for any stereoscopic reconstruction of loops in the east-west orientation.

    Feng et al.

  • Feng et al.