Ejection of cool plasma into the corona - comparison of 1D and 3D coronal loop models P.Zacharias1, S. Bingert2 & H. Peter2 1ISSI, Bern, Switzerland 2MPS, Katlenburg-Lindau, Germany Fifth Solar Orbiter Workshop September 10-14, 2012 - Brugge, Belgium

Ejection of cool plasma in 3D MHD model OVI 1032Å, log T=5.5 MgX 625Å, logT=6.0 box extension: 50 Mm x 30 Mm time covered: 60 min normalized currents current fluctuations Zacharias, Bingert & Peter 2011, A&A 532, A112 ➜ blob follows magnetic field lines ➜ cool compared to coronal plasma ➜ thermal pulse

Overview Our 3D MHD model - blob-like structure following magnetic field lines - result of heating event above chromosphere/thermal pulse Comparison with 1D loop model - confirm that thermal pulse leads to ejection of cool plasma into corona - investigate loop flows during heating phase - compare results to other 1D and 3D models Comparison with observations - search for similar features in Hinode/EUV imaging spectrometer (EIS) & SDO/Atmospheric Imaging Assembly (AIA) data synthesized images from 3D MHD model as AIA would observe the simulation in the He II 304 (left) and FeIX/X 171A (right) channel on the solar limb.

Blob characteristics in 3D MHD model moves along magnetic field lines (L=60 Mm) diameter: 4-5 Mm (depending on LOS) velocities: 50-100 km/s ≈ sound speed internal energy density: 1.5 mW m-3 ≈ HOhm ➜ pressure increase kinetic energy density: 0.1 mW m-3 ≈ -v grad p ➜ pushes plasma upward

Blob characteristics in 3D MHD model moves along magnetic field lines (L=60 Mm) diameter: 4-5 Mm (depending on LOS) velocities: 50-100 km/s ≈ sound speed internal energy density: 1.5 mW m-3 ≈ HOhm ➜ pressure increase kinetic energy density: 0.1 mW m-3 ≈ -v grad p ➜ pushes plasma upward

Blob characteristics in 3D MHD model moves along magnetic field lines (L=60 Mm) diameter: 4-5 Mm (depending on LOS) velocities: 50-100 km/s ≈ sound speed internal energy density: 1.5 mW m-3 ≈ HOhm ➜ pressure increase kinetic energy density: 0.1 mW m-3 ≈ -v grad p ➜ pushes plasma upward

(Zacharias et al., in prep.) 3D MHD model (Bingert et al. 2011) 1D loop model (Zacharias et al., in prep.) Pencil code (Brandenburg & Dobler 2002) semi-circular loop: L=60 Mm energy equation incl. heat cond., rad. losses & background heating term heating pulse: variation of amplitude, width, duration & position along loop Pencil code (Brandenburg & Dobler 2002) small AR simulation: 50x50x30 Mm3 energy equation incl. heat cond. & rad. losses heating mechanism: braiding of magnetic fieldlines (Parker 1972; 1983) by photospheric driver (Gudiksen & Nordlund 2002)

Temporal evolution of 1D coronal loop temperature profile space-time plot of temperature thermal pulse ➜ ejection of cool plasma into the corona

Comparison of different ejection heights space-time plot of temperature injection height increases by ≈ 10 km/image

Variation of heating pulse length and width space-time plot - temperature non-localized localized long short space-time plot - velocity v(tmax.heat)=22 km/s v(tstart)=5 km/s exclusively blueshifts during heating phase!

Comparison with other 1D and 3D models 3D MHD model (Hansteen et al. 2010): L≈7 Mm (network loops) - rapid heating of material in place results in overpressure - material is pushed upward into corona and downward towards chromosphere - > blueshifts in coronal lines & redshifts in TR lines 1D loop model (Spadaro et al. 2003): L≈5-10 Mm (network loops) - upflows during heating phase & downflows during cooling phase - but also redshifts during transient heating near loop footpoints Our 3D & 1D loop models: L≈60 Mm (AR loops) - thermal pulse leads to ejection of cool plasma into corona - only upflows during heating phase (so far) -> might be due to different loop lengths

Comparison with observations

Hinode / EIS observations HeII 256Å (logT=4.7) “sit and stare” observation: 1h - 2 min cadence movie courtesy David Williams (MSSL)

Hinode / EIS sit and stare observations snapshots - time lag: 4 min - He II 256Å (logT=4.7) ➜ bullet-like feature that presumably follows the magnetic field lines - visible in HeII 256Å channel of EIS - not visible in higher-T channels estimates: - diameter: ≈7-10 Mm - flight time: ≈30-35 min - velocity: ≈100 km/s

SDO / AIA observations ➜ bright blob in HeII 304Å (logT=4.9) ➜ no detection in FeIX 171Å (logT=5.9) FOV ≈ 49 Mm x 56 Mm diameter: ≈2-3 Mm flight time: ≈5 min velocity: ≈50-100 km/s thanks to Eamon Scullion!

Conclusions observational evidence of cool plasma ejecta in EIS & AIA data 1D loop model results: successful reproduction of ejection following injection of heating pulse -> confirms proposed mechanism in 3D model parameter study shows that whether or not ejection takes place depends on heating pulse injection height exclusively blueshifts during heating phase (preliminary) 3D model 1D model SDO/AIA 304Å