the dynamic chromosphere
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The Dynamic Chromosphere
Mats CarlssonInstitute of Theoretical Astrophysics, University of
OsloJAXA, November 20 2008
Semi-empirical model
VAL3C
Ca II H-line intensity
1D NLTE hydrodynamic modelling
SUMER observations
Carlsson, Judge, Wilhelm 1997
Ca H timeseries from Hinode
•Broad band filter contains too much photospheric signal for chromospheric diagnostics on-disk
3D models from convection zone to corona
•16x8x16 Mm (2 Mm below, 14 Mm above z=0)
•Open boundaries
•Detailed radiative transfer along 48 rays
•Multi-group opacities (4 bins) with scattering
•NLTE radiative losses in chromosphere (CaII, H)
•Optically thin losses in corona
•Conduction along field-lines
•Various initial magnetic field configurations
•No imposed driving (selfconsistent convection)
Hansteen 2004, Hansteen, Carlsson, Gudiksen 2007, Sykora, Hansteen, Carlsson 2008
Ca H timeseries from Hinode
Ca-H timeseries from model
Red field lines
Coloring is temperature
(red=chromosphere
green/blue= TR)
Carlsson & Hansteen
Heating of the middle chromosphere
•Chromosphere highly dynamic and filamentary
•Hot and cool gas coexist
•Non-magnetic chromosphere may be wholly dynamic
•Magnetic fields crucial for the understanding of chromospheric heating, dynamics and connection with upper layers
•Network chromosphere and internetwork mid-upper chromosphere magnetically heated
•Whole zoo of wavemodes
Ca emission at the limb
What can be done from the ground?
•Limb: scattering in atmosphere, difficult with adaptive optics
•Spectroscopy: Image restorations difficult
•Fabry-Perot: Hα, CaII 8542, photosphere
Examples taken from Oslo-group observations at the Swedish 1m Solar Telescope (SST) on La Palma
Hα blue wing at SST, Aug 10, 2007
SST: CaII 866.2
Red Blue
Spectroscopy
Fabry-Perot
•Swedish 1m Solar Telescope on La Palma
•CRISP
•Ca II 854.2 nm, spectral resolution 90 mÅ
•29 line positions -1900 mÅ to +1900 mÅ, step 100-200 mÅ, 11s cadence (full scan)
•24 line positions -900 mÅ to +190 mÅ, step 50 mÅ, 9s cadence (full scan), 33 min timeseries
•diffraction limited (0.21”) (after MOMFBD restoration), 0.071”/pixel, FOV 66”x67”
• June 13-15 2008
Hα observations with SST
• June 15th 2008
•CRISP Fabry-Perot
•25 line positions -1800mÅ to +800mÅ, step 100mÅ, spectral resolution 60mÅ
•6.7s cadence (full scan), 30 minutes timeseries
•diffraction limited (0.16”), 0.071”/pixel, FOV 66”x67”
Hα line center
-800 mÅ
+800 mÅ
Why space?
•UV gives much better diagnostics for the chromosphere (91.2-152 nm, Mg II 280 nm)
•spectroscopy
•observing across β=1
•coupling to transition region-corona
•consistent time-series of any target
What do we need?•UV
•High spatial and temporal resolution
•0.2”, 1-10s
•Spectroscopic capability
• line shapes, 1 km/s
•Polarimetry
•3D radiation-MHD combined with 3D NLTE modelling
•20 km resolution: 10243 : 4 months on 1000 cores
Conclusions
•Chromosphere is very dynamic and structured with small scales
•Absolutely essential to have diagnostics from chromospheric plasmas together with higher temperature plasmas
•Need 3D radiation-MHD modelling
•Need mission like Solar-C plan B
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