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