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Flows in hot coronal loops : mass cycle and coupling from chromosphere to corona

Flows in hot coronal loops : mass cycle and coupling from chromosphere to corona. Pia Zacharias, Sven Bingert , Hardi Peter Solar Cycle 24 Napa , California December 11, 2008. 10.  10 5 K.  6.5 10 5 K . 5. 0. Peter (1999) ApJ 516, 490 .

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Flows in hot coronal loops : mass cycle and coupling from chromosphere to corona

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  1. Flows in hot coronalloops:masscycle and couplingfromchromosphere to corona Pia Zacharias, Sven Bingert, Hardi Peter Solar Cycle 24 Napa, California December 11, 2008

  2. 10  105 K  6.5105 K 5 0 Peter (1999) ApJ 516, 490 Dopplershift [ km/s ] 5 10 SUMER Doppler shifts in the solar transitionregionand in thecorona

  3. 3D simulation – Doppler shifts Observation Simulation Probably OK for TR (some 105 K) Not yet good forcoronallines

  4. Fromobservation to simulation • Input magneticfield - quietSun-like • 3D MHD model of coronal box (50x50x30Mm3=2563) (Bingert at al.) • includingradiativeloss, heatconduction and Ohmicheatingdue to fluxbraiding • Spectralsynthesis (CHIANTI)  Resultingloopstructures Initial verticalmagneticfield at bottomboundary Evolving TR loops (snapshop)

  5. Doppler velocities in thesimulation CIV (1548 Å) Doppler map Distribution of Doppler velocities (smaller FWHM thanobserved; 3x) <vD>=1.52 km/s meanredshift blueshiftredshift

  6. Global massbalance: constantcoronalmass • Coronalmassfluctuates ≈ 0.1% • Emptycoronaoversimulation time (30 min) wouldneedaverageflow of ≈ max 0.1 km/s • Global sinking of atmospheredue to masslossisNOTresponsiblefornetlineshift N: Number of particles in the box with T>104.1 K <N>: meannumber of particles in the box with T>104.1 K

  7. Investigation of individualloops: hotloops • 1st step: restrain to L > 30 Mm andTmax > 105 K • Assignthesamefieldlines at eachtimestep followfieldlinesthroughthe 30 minute time series snapshot

  8. Nature of theflows in hot and longloops log(T[K])>105 & L>30 Mm Contradiction: Whyisthecoronalmassconstantwhiledownflowsdominate ? Solution ? Coronalmasssupply throughtheheating of cool loops? 27 % 62 % 10 % Siphon flows: Flowthroughtheloop Draining / downflows Flow out of theloop Strange flowprofiles

  9. Heatingloopswithupflows? heating Problem: Even loopsthatareheated up aredraining... Whereareloopswhichfill due to increasingheatinput ? Probablyselectioneffect (T>105K) ? downflow  NO hot loopswithupflowsfound!

  10. Outlook • Properlyfollowfieldlines in time • Whatabouttheupflowswesee in the Doppler maps? • Investigate “cool“ loops (T<105 K) withsamelengths

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