SPW5 Ascona

Chromospheric magnetic fields with the EST:A new era for He 10830Andreas LaggMPI for Solar System ResearchKatlenburg-Lindau, Germanylagg@mps.mpg.de

EST France 2010 Workshop, May 19-21 2010MotivationWhy He 10830?purely chromosphericB-range 1 G to several kGideal for coupling scienceheight diagnostic tool!off-limb AND on-disk easy to interpret

2EST France 2010 Workshop, May 19-21 2010MotivationWhy with EST?photon efficiency high photon fluxspatial & temp. resolutionhigh polarimetric accuracy(polarization-free telescope)image stability (MCAO)

3EST France 2010 Workshop, May 19-21 2010Ionization / Recombination Scheme

Centeno et al., 2008Advantage: NO photospheric contribution!Disadvantage: Coronal illumination required4EST France 2010 Workshop, May 19-21 2010Para / Ortho Helium

Centeno et al., 20085EST France 2010 Workshop, May 19-21 2010He 10830Formation Height

Avrett et al. (1994)6EST France 2010 Workshop, May 19-21 2010Chromosphere extremely warped surface. this is a problem - stratification not so easy to determine.Solution: Stereoscopy, Off-Limb, OR: He 10830

He 10830Formation Heightimportant parameters for He formation:density and extent of chromospherecoronal illuminationAvrett et al. (1994)He density 3S17plagebright networkcell centeraverageEST France 2010 Workshop, May 19-21 2010cool He loops can extend to much higher layers

model atmospheres:T-profile (hydrost. equ.) pressuremodels A (cell-center), C (average), F (bright network), P (plage)CH/CL hi/lo coronal irradiance

He 10830Formation Heightimportant parameters for He formation:density and extent of chromospherecoronal illuminationAvrett et al. (1994)

8He density 3S1Wavelength []Stokes IEST France 2010 Workshop, May 19-21 2010model atmospheres:T-profile (hydrost. equ.) pressuremodels A (cell-center), C (average), F (bright network), P (plage)CH/CL hi/lo coronal irradiance

He 10830Photospheric ContributionNone.No complex non-LTE modelling of the solar atmosphere required.Simple interpretation analysis of complex solar conditions possible9EST France 2010 Workshop, May 19-21 2010

He 10830Analysis TechniquesAdvanced inversion codes available:HAZEL (Asensio Ramos et al. 2008)(HAnle and ZEeman Light)HeLIX+ (Lagg et al., 2009)(Helium Line Information Extractor),based on similar synthesis module

10EST France 2010 Workshop, May 19-21 2010Sensitivity of He 10830 to magnetic fieldAnimation next slide:INC=80 to solar verticalformation height: 2000 kmbroadening: 8 km/s optical thickness: model C0