Inclinations of small quiet-sun magnetic features

Transcription

1 Inclinations of small quiet-sun magnetic features Shahin Jafarzadeh Max Planck Institute for Solar System Research Sami K. Solanki, Andreas Lagg, Michiel van Noort, Alex Feller, Sanja Danilovic Max Planck Institute for Solar System Research Luis R. Bellot Rubio Instituto de Astrofísica de Andalucía (IAA-CSIC), Spain

2 Sunrise Diffraction limit: 0.1 arcsec 6 Days Flight at 37 km altitude (June 2009) SuFI (SUNRISE Filter Imager): 214 nm, 300nm, 312 nm (OH), 388 nm (CN) and 397nm (Ca II H) FOV: 14" x 40" IMaX (IMaging Magneto -graph experiment): Full Stokes Spectropolarimetry in Fe I nm FOV: 50" x 50" A 1-m Balloon-Borne Solar Telescope Barthol, P. et al., 2011, Sol. Phys., 268, 1

3 Magnetic Field Inclination in internetwork areas Horizontal magnetic field everywhere in the internetwork (e.g., Lites et al. 1996; Orozco Suárez et al. 2007; Lites et al. 2008; Orozco Suárez and Bellot Rubio 2012; Bellot Rubio and Orozco Suárez 2012) determined to a large part by inversions Normalised Frequency Inclination [deg] Vertical fields from simulations: Borrero & Kobel 2011, 2012 Isotropic fields: Asensio Ramos 2009; Bommier et al Predominantly vertical fields (line ratio): Stenflo 2010, 2013

4 Field Inclination Measurements: (1) Inversions At the position of internetwork MBPs (Magnetic Bright Points): Three Inversion Codes: SPINOR (Frutiger et al. 2000) SIR (Ruiz Cobo & Del Toro Iniesta 1992) VFISV (Borrero et al., 2011) Differently Treated Data (different noise levels) non-reconstructed spatially smoothed, non-reconstructed

5 Distributions of Field Inclination At the position of internetwork MBPs (Magnetic Bright Points): Normalised Frequency Inclination [deg] From Inversions: SPINOR: Non-reconstructed, spatially smoothed Non-reconstructed SIR: VFISV: Non-reconstructed (dashed line) Consistent with previous studies

6 Magnetic Flux Tubes Thin Flux tubes: Bundles of magnetic field lines, concentrated between granules on the surface. Magnetic Bright Points: Cross-sections of Flux Tubes Courtesy of: M. van Noort & L. R. van der Voort (2004)

7 Magnetic Flux Tubes Thin Flux tubes: Bundles of magnetic field lines, concentrated between granules on the surface. SuFI Ca II H IMaX 525 nm line-core Magnetic Bright Points: Cross-sections of Flux Tubes IMaX CP Map IMaX 525 nm continuum Not to scale Courtesy of: M. van Noort & L. R. van der Voort (2004)

8 Field Inclination Measurements: (2) Geometric Method [arcsec] gp [arcsec] [arcsec] Locating & connecting small-scale MBPs (with CP>4σ) in IMaX continuum and line-core, with approximately 300 ± 100 km height difference Finding the angle between the connecting line & the LOS.

9 Field Inclination Measurements: (2) Geometric Method 40 Three combinations of: IMaX Continuum - IMaX Line-core 30 [arcsec] gp km) (height difference 300 IMaX Continuum - SuFI Ca II H 20 (height difference 500 km) IMaX Stokes V made in inner/outer flanks of the line 10 (height difference 50 km) [arcsec] [arcsec] Locating & connecting small-scale MBPs (with CP>4σ) in IMaX continuum and line-core, with approximately 300 ± 100 km height difference Finding the angle between the connecting line & the LOS.

10 Distributions of Field Inclination From our Geometric Method: IMaX continuum - IMaX line-core IMaX continuum - SuFI Ca II H IMaX Stokes V made in inner/outer flanks of the line Normalised Frequency Inclination [deg] From Inversions: SPINOR: Non-reconstructed, spatially smoothed Non-reconstructed SIR: VFISV: Non-reconstructed (dashed line)

11 Distributions of CP and LP Measure of Circular Polarization (CP) and Linear Polarization (LP) signals, determined at the position of the MBPs. 4σ 1σ 2σ 3σ Normalised Frequency (a) (b) CP [%] LP [%]

12 Conclusions Major advances from the SUNRISE high resolution (seeing-free) data: Introducing a new (geometric) approach to determine inclination of the magnetic field in internetwork MBPs independent of Stokes profiles The Nearly vertical magnetic field (from our geometric method) is clearly incompatible with the rather horizontal magnetic fields (from the inversions) (at the position of internetwork MBPs) Inversions overestimated horizontal flux by an order of magnitude (at the position of internetwork MBPs) We Suggest the proposed measurements as a complementary approach to inversions of Stokes parameters for determining the field inclination

13 Thank you