1. 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

2. Dimming regions of 13/05/05

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

4. Intensity evolution (35 hr) selected regions1 2 3 4 5 6 7 8
Away from core 1
Away from core 2
Intensity
Time
Data gap: 17: :58 UT 1 2 3 4 5 6 7 8
Quiet Sun
Coronal Hole

5. Magnetic flux dimmings (20 G filter)1 2 3 4 5 6 7 8
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.

6. How do the dimmings form?7 3 4 1 2 3 4 5 6 7 8
From SolarSoft Latest events archive. PFSS Derosa & Schrijver 1 2
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.