1. SJC 2/28/2002Steady Flows Detected in EUV Loops 1 Steady Flows Detected in Extreme-Ultraviolet Loops Winebarger, A.R., Warren, H., van Ballegooijen, A. Deluca, E.E., Golub, L. Presented by Henry (Trae) Winter III

2. SJC 2/28/2002Steady Flows Detected in EUV Loops 2 Why This Paper ? NOT because it was short Based on observations Launching point for a discussion on coronal loop properties –General properties/assumptions –Important equations –Loop heating properties

3. SJC 2/28/2002Steady Flows Detected in EUV Loops 3 General Outline I.General Assumptions About Coronal Loops II.Basic Equations Used In Modeling & Observing Loops III.Observations & Interpretations IV.Critiques

4. SJC 2/28/2002Steady Flows Detected in EUV Loops 4 General Assumptions About Stationary Loops Rosner, Tucker, & Vaina. 1978 ApJ. (RTV) Serio, et al. 1981, ApJ. (RTVS) Symmetrical semicircular loops Constant width Magnetic field only defines geometry

5. SJC 2/28/2002Steady Flows Detected in EUV Loops 5 For hydrostatic loops: Hottest material is located at the loop top –Caveats Rayleigh-Taylor instabilities General Assumptions About Stationary Loops

6. SJC 2/28/2002Steady Flows Detected in EUV Loops 6 General Assumptions About Stationary Loops

7. SJC 2/28/2002Steady Flows Detected in EUV Loops 7 RTVS predicts a steep temperature rise from footpoint to T.R. and slow rise through T.R RTVS predicts an observable intensity decrease from footpoint to apex due to an exponential decrease in pressure due to gravity Predictions About Stationary Loops From RTVS

8. SJC 2/28/2002Steady Flows Detected in EUV Loops 8 Basic Equations Used In Modeling Stationary Loops Energy Balance Equation Conductive Loss Rate Radiative Loss Rate Heating Rate

9. SJC 2/28/2002Steady Flows Detected in EUV Loops 9 Basic Equations Used In Observing Loops Flux Equation Line Ratios (Isothermal Approximation)

10. SJC 2/28/2002Steady Flows Detected in EUV Loops 10 OBS: A loop in TRACE that showed very little intensity change over two hours INT: Stable loop structure OBS: A ratio between the TRACE 195Å/171Å filters as well as CDS line ratios is used as a temp. diagnostic. Temp Constant K INT: Does not agree with RTVS predictions OBS: A loop showed showed no exponential intensity decrease with height INT: Does not agree with RTVS predictions Observations & Interpretations I

11. SJC 2/28/2002Steady Flows Detected in EUV Loops 11 Figure 1

12. SJC 2/28/2002Steady Flows Detected in EUV Loops 12 OBS: Red shift in the SUMER Ne VIII 770 (10 5.8 K) line which corresponds to a line of sight velocity of 15-40 km s -1 +/- 5 km s -1. INT: Loop is not in hydrostatic equilibrium but instead has a steady flow. Observations & Interpretations II

13. SJC 2/28/2002Steady Flows Detected in EUV Loops 13 Figure 2

14. SJC 2/28/2002Steady Flows Detected in EUV Loops 14 New Model Use a non symmetric heating function to induce a steady flow and compare numerical solutions to the hydrodynamic problem to the observations

15. SJC 2/28/2002Steady Flows Detected in EUV Loops 15 Figure 3

16. SJC 2/28/2002Steady Flows Detected in EUV Loops 16 Critiques Isothermal approx Redshift /Blueshift Redshift shift

17. SJC 2/28/2002Steady Flows Detected in EUV Loops 17 Critiques

18. SJC 2/28/2002Steady Flows Detected in EUV Loops 18