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This is not another 12th May 1997.

Coronal dimming analysis of 13th May 2005 event. Gemma Attrill CfA/SAO. 12/05/97. 13/05/05. This is not another 12th May 1997. 13th May 2005 is more complex because it follows solar maximum: residue magnetic fields. Complexity reflected in the coronal dimmings. 2.

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This is not another 12th May 1997.

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  1. Coronal dimming analysis of 13th May 2005 event Gemma Attrill CfA/SAO 12/05/97 13/05/05 • This is not another 12th May 1997. • 13th May 2005 is more complex because it follows solar maximum: residue magnetic fields.

  2. Complexity reflected in the coronal dimmings

  3. 2 5 4 3 1 6 7 8 Intensity 7 8 1 3 2 Time Away from core 1 5 4 Away from core 2 6 Data gap: 17:37 - 22:58 UT Intensity evolution (35 hr) selected regions Quiet Sun Coronal Hole

  4. Existing coronal hole and extended dimming Previous rotation 17th April Post-eruption:13th May Pre-eruption 13th May Extended CH is there all the time. But obscured by overlying loops pre-eruption. These loops are removed during the eruption.

  5. 7 8 1 3 2 5 4 6 Old MDI data - not recalibrated: How are these loops involved in the eruption? • Do they play a crucial role in making the footprint of the eruption so large-scale? • Need to understand remote, secondary dimmings too.

  6. Small clues… Plus global-scale coronal wave too!

  7. Verification: 10th April 8th May

  8. Dimming analysis 13/05/05 Gemma Attrill Mullard Space Science Laboratory This is not another 12/05/97. 13/05/05 is more complex because it follows solar maximum: residue magnetic fields. 12/05/97 13/05/05

  9. Dimming regions of 13/05/05

  10. Attrill et al., (2006) Selecting regions for analysis

  11. 2 5 4 3 1 6 7 8 Intensity 7 8 1 3 2 Time Away from core 1 5 4 Away from core 2 6 Data gap: 17:37 - 22:58 UT Intensity evolution (35 hr) selected regions Quiet Sun Coronal Hole

  12. 7 8 1 3 2 5 4 6 Magnetic flux dimmings (20 G filter) If dimmings 1 and 2 mark flux rope footpoints, then minimum magnetic flux of the flux rope: ((Absolute 1 + Absolute 2) / 2) = 3.98E+21 Mx c.f. Yurchyshyn et al., (2006) use an Erupting Flux Rope model and Hu et al., (2006) use the Grad-Shafranov model: Axial (torroidal) flux in ICME = 2.9E+21 Mx, 2.1E+21 Mx Azimuthal (poloidal) flux in ICME = 4.4E+22 Mx, 4.2E+21 Mx Our magnetic flux measurement (which is a minimum), is too large to be explained just by the axial (torroidal) magnetic flux. So the azimuthal (poloidal) magnetic flux is also required.

  13. 3 1 2 4 7 7 8 1 3 2 5 4 6 From SolarSoft Latest events archive. PFSS Derosa & Schrijver How do the dimmings form? Analysis of the evolution of the dimmings can give a lot of information (both quantitative & qualitative) regarding the changing magnetic topology of the CME event.

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