Soft X-ray heating of the chromosphere during solar flares A. Berlicki 1,2
The Dynamic Chromosphere
description
Transcript of The Dynamic Chromosphere
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