1. Measurements of photospheric magnetic field within and around sunspots Rolf Schlichenmaier, Kiepenheuer-Institut für Sonnenphysik ENS, 29.Mai 2006 Image: DOT, Sütterlin

2. The magnetic Sun in the photosphere ► Quiet Sun normal granulation ► Active (magnetic) regions: Plage Faculae Sunspots & pores Active regions ► Plage & Faculae: Bright points Filigree Magnetic knots ► Sunspots Umbra umbral dots light bridge Penumbra penumbral filaments Evershed flow Dark cores VTT, von der Lühe

3. Part I: Sunspots Peculiarities of Penumbra The magnetic field: The Uncombed Penumbra Sunspot image with HOAO at DST: Wöger & Rimmele 2005 The flow field (Evershed effect) Properties of fine structure

4. Speckle-reconstructed image

5. Best single image with high-order AO

6. (DOT, La Palma, Sütterlin, 9 August 2003) Peculiarities of the Penumbra HOAO at DST: Wöger & Rimmele 2005

7. 2D Spectroscopy of Fe I 557.6 nm

8. Line parameters of Fe I 557.6 nm (Tritschler, Schl., Bellot Rubio, & KAOS team 2004)

9. Penumbral line asymmetries: bisectors Schl., Bellot Rubio, Tritschler 2004 Findings: Kinks and Reversals Explanation: Downflows (red-shifts) in deep layers

10. Line asymmetries of unmagnetic lines

11. Penumbral bisectors: Findings Schl., Bellot Rubio, Tritschler 2004

12. Observation of the flow geometrie Inner PU: Upflow in bright component. Outer PU: Downflow in dark component. Schl. & Schmidt 2000

13. Line of sight velocity on limb side Bright: red-shift Dark: blue-shift Filtergram Dopplergram (line wing of Fe I 557.6 nm) Heliocentric angle: 30 o (Rimmele 2006) ► Flow filaments: Upflow turns into outflow. ► Flow is present in both, bright and dark locations: - Bright grains in inner penumbra are associated with upflows - Radial outflow predominantly present in dark filaments

14. Dark cored penumbral filaments: dark cores Discovery of dark cores (Scharmer et al. 2002)

15. Evolution of penumbral fine structure (SST, Scharmer et al. 2002)

16. Dark core spectroscopy I Dark cores produce spikes in spectrum! Bellot Rubio, Langhans, Schl. 2005

17. Dark core spectroscopy II Dark cores shifted relative to lateral brightenings! Outward flow, essentially horizontal with small upflow component. Bellot Rubio, Langhans, Schl. 2005

18. Spectropolarimetry TIP@VTT

19. Spectropolarimetry in the infrared and the visible at the VTT POLIS TIP Beck et al. 2005

20. Stokes-V asymmetries Schl. & Collados 2002 Magnetic neutral line

21. Two-component inversion

22. 2nd component 1st component 2nd component The magnetic field vector and line of sight velocity Bellot Rubio, Balthasar, Collados, Schl. 2003 Inclination LOS velocity Field strength

23. Magnetic field angle and flow speed of 2nd component

24. Modelling the penumbra Image design: Daniel Müller Dynamic flux tubes embedded in a sunspot

25. The moving tube model: simulation (Schl., Jahn, & Schmidt 1998)

26. The moving tube model: simulation (Schl., Jahn, & Schmidt 1998)

27. The moving tube model: simulation Schl., Jahn, & Schmidt 1998

28. The sea serpent Schl. 2002

29. Consequences of the Moving Tube Scenario Penumbral grain: PG tails: PG inward migration: Evershed flow: Downflow in outer PU: Uncombed penumbra: Surplus brightness of PU: Formation of penumbra: Footpoint of tube Radiative cooling Footpoint migration Flow along tube Sea serpent solution Tube in background Hot upflows Angle of magnetopause 61014 Temperature [1000 K]

30. Observational evidence for embedded flow channel

31. Comparison: Measurements and theoretical prediction (Schl., Müller, Steiner, Stix 2002; Müller et al. 2002; Beck et al. 2006)

32. Summary of part I on sunspots Sunspot penumbra is not homogenous: Flow: concentrated in deep photosphere (log  au > 1). horizontally, but components of up- and down-flows. Dark cores associated with flow. Uncombed penumbra: Two components Background: extension of umbral magnetic field. Inclined flow component: Peculiarity of penumbra; responsible for fine structure and surplus brightness (relativ to umbra). Embedded flow channel (discontinuities along the LOS) necessary to reproduce observed NCP! Lateral scale of fine structure about 0.2 arcsec. Next steps: 3D radiative magneto-convection in inclined magnetic field. Spectro-polarimetric observations that resolve intrinsic structure of penumbra: New instrumentation for existing telescopes SOLAR-B, GREGOR, SUNRISE, ATST!

33. G-Band image (~430 nm) VTT, von der Lühe Zoom in on next slide Part II: Magnetic elements

34. Normal granulation Bright points (point like) Filigree (sheet like) Abnormal granulation: Magnetic knots not visible? Micropore? G-Band image (~430 nm)

35. Facular regions: Same as plage regions close to the solar limb.

36. Dynamic evolution of magnetic elements (SST, Rouppe van der Voort et al. 2006)

37. Properties of magnetic elements from spectropolarimetric measurements: Bright points in the moat of a sunspot Beck, Bellot Rubio, Schl., Sütterlin 2006

38. Interpretation with help of inversion Inversion with all lines: Magnetic and non-magnetic component

39. Properties of G-Band bright points (BPs): results I 94% of BPs are magnetic Field strengths of BPs vary BP contrast slightly increases with field strength

40. Properties of G-Band bright points (BPs): results II BP contrast decreases with angle to LOS Magnetic component hotter by some 1000 K at equal optical depth Temperature tends to decrease with increasing magnetic flux: Hot wall effect unimportant for large flux tubes

41. Measurement of magnetic field strength Weak field regime: magnetic flux scales with V-amplitude (thermal broadening) |B| can only be determined if filling factor (of magnetic field) is known. Strong field regime:|B| scales with separation of V-lobes With Fe I 1564.8 nm strong field regime down to some 400 Gauss.

42. Magnetic elements in the quiet Sun Internetwork magnetic fields are WEAK, and not of kGauss strength! Fe 630.2 nm InternetworkNetwork Fe I 1564.8 nm (g=3) Internetwork Khomenko et al. 2003Rezaei, Beck, Schmidt, Schl. 2006 High spatial resolution (<1arcsec)

43. Summary of part II on magnetic elements G-Band Bright points: BPs are magnetic. Properties consistent with classical picture (hot wall effect). BPs are not unique features (as, e.g., a static well-defined flux tube), but cover a large parameter space. Magnetic field strength varies between 500 and 1500 Gauss. Internetwork fields in the quiet Sun: Magnetic field is predominantly weak (a few hundred Gauss) Strong fields of more than 1000 G are rare.