1. Cross-Sectional Properties of Coronal Loops and Their Implications Henry “Trae” Winter III with Chester Curme

2. Constant Cross- Section? Klimchuk et al. 1992 Studied 10 SXT loops Measured an Apex to Footpoint Expansion Factor of

3. TRACE Loops Watko & Klimchuk, 2000 22 Loops Lopéz Fuentes et al, 2006 20 Loops

4. DeForest, 2007

6. Unresolved Structures

7. Lopés Fuentes et al, 2008 Countered DeForest’s argument Claimed that their method could distinguish between unresolved expanding and not expanding but resolved strands Conversation switched to theories that predict constant cross-section loops (i.e. Constant B).

8. How Could Loops be of Constant Cross-Section? Twist? (Klimchuk et al., 2000) Separators? (Plowman et al., 2009)

9. How Could Loops be of Constant Cross-Section? Emission loops (eLoops) do not actually trace field lines (Peter & Bingert, 2012)

11. Apex Temperature Evolution

12. Apex Density Evolution

13. Over Pressure

14. Synthetic Obs. 171 1.0 1.31.21.12.01.51.44.03.05.0 AIA Pixel Size Hi-C Pixel Size

15. Synthetic Obs. 335 1.0 1.31.21.12.01.51.44.03.05.0 AIA Pixel Size Hi-C Pixel Size

16. zz Width Measurements

17. Estimation of Width AIA171

18. Estimation of Width AIA 335

19. zz Estimation of Width “Hi-C Like”171

20. Estimation of Width “Hi-C Like” 335

21. Summary Loop geometry has an effect on fundamental loop properties such as temperature and density (pressure) Vesecky, Antiochos, and Underwood, 1979; Mariska, 1984; Schrijver, Lemen and Mewe, 1989; Dowdy, Emslie, and Moore, 1987 Modeled near-resolution, expanding loops can appear to be of constant cross-section just like those “pesky” observations Loops must be many pixels wide to make width determinations Is it safe to use magnetic fields to generate loop geometries for 1D models?

22. Extra Slides

23. See Anna Malanushenko’s Work at the SPD

29. How Could Loops be of Constant Cross-Section? Twist? (Klimchuk et al., 2000)

30. How Could Loops be of Constant Cross-Section? Separators? (Plowman et al., 2009)

31. How Could Loops be of Constant Cross-Section? Maybe eLoops do not trace out magnetic fields? (Peter & Bingert, 2012)

32. How Could Loops be of Constant Cross-Section? Peter & Bingert, 2012

33. What happens if loops are not of constant cross- section?

35. Brooks, et al 2013