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Hiroaki Isobe (Kyoto Univ) contributed by:

High-res spectroscopic observations in chromosphere science goal of plan B / results from Hinode-Hida obs. Hiroaki Isobe (Kyoto Univ) contributed by: S. Ueno, H. Watanabe, Y. Hashimoto, K. Otsuji, R. Kitai, K. Ichimoto,

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Hiroaki Isobe (Kyoto Univ) contributed by:

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  1. High-res spectroscopic observations inchromospherescience goal of plan B / results from Hinode-Hida obs Hiroaki Isobe (Kyoto Univ) contributed by: S. Ueno, H. Watanabe, Y. Hashimoto, K. Otsuji, R. Kitai, K. Ichimoto, K. Shibata, S. Nagata,, T. Anan, S. Morita (Kyoto U.) and Hida/DST team Y. Katsukawa, R. Ishikawa (NAOJ) and SOT team V. Krishan (Indian Inst. Astrophys. Bangalore)

  2. Scientific motivation of Solar-C • Plan A: Generation of magnetic field • and its dissipation in polar region • Plan B: Dissipation of magnetic field • and its local generation

  3. How fast can magnetic field dissipate?- fundamental process in astrophysics - • Dissipation in fully ionized (collisionless) plasmas • high energy phenomena in astrophysics (GRB, AGN, Blackhole accretion disks, magnetors…) • solar corona (and Earth magnetosphere) is the best lab • significant progresses coming from Hinode • Dissipation in weakly ionized, collisional plasmas • flux removal of collapsing molecular clouds => origin of stars • MRI and dynamo in protoplanetary disks => origin of planets (and life) • photo/chromoshpere is the best lab

  4. In astrophysics… Uzdensky (2006, astro-ph/0607656) … the most important reconnection mechanism in Astrophysics invokes waves, a certain type of waves, in fact. Called handwaves (See Fig 1). The mechanism works like this: Well, we know that fast reconnection happens in the Solar corona, and in the Earth magnetosphere. So it should also happen in OUR astrophysical system. Solar physicists have a huge responsibility.

  5. wave Small-scale fields and corona/solar wind • Ubiquitous small-scale horizontal fields found by SOT (Lites+ 2007) • Granular-scale emerging fluxes have Poyinting flux comparable to what is required to heat the corona (≈ 106-7 erg cm-2 s-1; Ishikawa & Tsuneta 2009) • Maybe more? (Trujillo Bueno+ 2002) Ishikawa et al. (2008) Bvertical Bhorizontal ≈1000km I Poynting flux can be transported by interaction with the vertical flux (Isobe, Proctor & Weiss 2008)

  6. Chromospheric reconnection produces high-frequency waves Wavelet spectrum of Vx in corona log period ≈10s Wavelet spectrum of Vx in photosphere ≈5min log period Isobe, Proctor & Weiss (2008)

  7. Is fast reconnection possible in chromosphere? • Fast reconnection: Vreconnection≈ 0.1VAlfven(and independent on resistivity) • Extensive studies done for collisionless plasmas • micro: anomalous resistivity by kinetic effects (wave-particle interaction) • macro: Petschek-type slow shock • scale coupling • Chromosphere is fully collisional and weakly ionized • But magnetic Reynolds # is still large: S = VAL/η ≈ 105 • Classical Sweet-Parker reconnection seems too slow (e.g., Chae et al. 2002) • Hall or ambipolar effects?

  8. Hall and Ambipolar effects Induction equation of weakly ionized plasma Hall term (Ion-electron) Ambipolar term (Ion-neutral) • Ambipolar/Hall = ωci/νin • ωci : Ion-cyclotron freq ∝B • νin : Ion-neutral collision freq ∝ n Chromosphere: Ambipolar > Hall, resistive Photosphere: Hall > ambipolar, resistive Important only in small scale, e.g., current sheets and high-frequency waves.

  9. When Hall/Ambipolar become significant Hall > Advection => 0.1〜1 s in photosphere Ambipolar > Advection => 0.1〜1 s in chromosphere Length scale ≈ tVna= c/ωpi (nn/ni)1/2≈ 1-10km (c/ωpi : inertia length) => Detection more likely in temporal variation • * Possibly important in local dynamo, too (Krishan & Gangadhara 2008)

  10. MHD+ambipolar reconnection (Isobe, Krishan & Shibata in prep) Resistive only Resistive + ambipolar • Ambipolar effect sharpens the current sheet (Chitre & Krishan 2001) • Enhance the reconnection rate • Create smaller plasmoids => higher frequency wave

  11. Coordinated observation of Hinode and CaH/K spectroscopy at Hida observatory 60cm Domeless Solar Telescope (DST) at Hida Observatory, Kyoto Univ.

  12. high chromosphere red shifted blue shifted photosphere red shift Chromospheric response to umbral dots(H. Watanabe et al.) SOT/CaH 2007 Aug 08 umbral dot dark umbra CaH Wavelength (A) Bisector analysys => LOS velocity at different heights

  13. Ellerman bomb(Hashimoto et al.) SMART/Hα, 2007/08/10 SOT/Ca H SOT/CaH SOT/StokesV 10”

  14. Reconnection modified by chromo. oscillation? Isobe, Tripathi & Archontis (2007) Time DST Ca II H spectra Blue enhancement • EB: Reconnection of neighboring loops in lower chromosphere • Alternative blue and red enhancement with a period of a few min • Reconnection modified by chormospheric oscillation? (Chen & Priest 2006) Red enhancement ≈ 2min target 3968.49Å 1Å Hashimoto et al.

  15. CaH line profile −: Fitted profile calculated with MULTI-code * : Observed profiles Jet Quiet region Chromospheric jets (S. Ueno et al.) SOT/Ca II H Hida/DST SpectroheliogramCa II h3 − 0.5 Å Shibata et al. 2007

  16. Doppler Velocity upward ReconnectionPoint ? downward Fitting by MULTI => atmospheric structure Temperature • Bidirectional flow (≈ 20km/s) => reconnection point in the middle? • Plane-of-sky velocity measured from SOT image ≈ 40km/s • Significant enhancement in temperature and density

  17. Ca II H / h2 Hida/DST Jet-like feature in QS At the bright point at the footpoint of jet. • Velocity downward (at the footpoint) throughout photosphere. Reconnection point above? • No enhancement in temperature and density upward Doppler Velocity ReconnectionPoint ? downward

  18. Alfvenic/Okamotic waves in prominence Isobe et al. disk SOT/BFI prominence Pseudo-SOT from DST SOT/CaH

  19. Doppler velocity time Intensity time • Black (red) lines trace the peaks/valleys in Doppler velocity (intensity). • Phase velocity of Doppler V = 10-40 km/s • No corresponding phase shift in intensity => imcompressible waves

  20. Conclusions • Chromosphere is • perhaps playing essential role in coronal heating and solar wind • unique laboratory for weakly ionized plasmas in astrophysics • Ground-based observations seem to catch the signatures of waves and reconnections • What we need more? • spectropolarimetric diagnostics with SOT-level resolution, in various layers • B, V, N(Alfven vel/collition freq), T(ionization, β) • temporal resolution <1s • For what?

  21. My answer: Solar-C(plan B) will • Determine the reconnection rate as a function of plasma parameters • from photosphere to corona • quantitative measurement essential (B, V, N, T) • Basis/frontier of astrophysics • Probe the diffusion region • Hall/ambipolar effects • scale coupling • explore new physics Shibata+ 2007

  22. With Solar-C (A and B), we will be running the frontier of physics and astrophysics. I am happy to devote next 10 years for it.

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