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Steady Flows Detected in Extreme-Ultraviolet Loops

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. Why This Paper ?. NOT because it was short Based on observations

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Steady Flows Detected in Extreme-Ultraviolet Loops

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  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 Steady 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 Steady Flows Detected in EUV Loops

  3. General Outline • General Assumptions About Coronal Loops • Basic Equations Used In Modeling & Observing Loops • Observations & Interpretations • Critiques Steady Flows Detected in EUV Loops

  4. L 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 Steady Flows Detected in EUV Loops

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

  6. General Assumptions About Stationary Loops Steady Flows Detected in EUV Loops

  7. Predictions About Stationary Loops From RTVS • 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 Steady Flows Detected in EUV Loops

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

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

  10. Observations & Interpretations I 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 Steady Flows Detected in EUV Loops

  11. Figure 1 Steady Flows Detected in EUV Loops

  12. Observations & Interpretations II OBS: Red shift in the SUMER Ne VIII 770 (105.8 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. Steady Flows Detected in EUV Loops

  13. Figure 2 Steady 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 Steady Flows Detected in EUV Loops

  15. Figure 3 Steady Flows Detected in EUV Loops

  16. Critiques • Isothermal approx • Redshift /Blueshift • Redshift shift Steady Flows Detected in EUV Loops

  17. Critiques Steady Flows Detected in EUV Loops

  18. Steady Flows Detected in EUV Loops

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