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, 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) Plan A: Generation of magnetic field and its dissipation in polar region Plan B: Dissipation of magnetic field and its local generation Scientific motivation of Solar-C 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 In astrophysics Uzdensky (2006, astro-ph/ ) 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. 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 ( erg cm -2 s -1 ; Ishikawa & Tsuneta 2009) Maybe more? (Trujillo Bueno+ 2002) wave Poynting flux can be transported by interaction with the vertical flux (Isobe, Proctor & Weiss 2008) B vertical B horizontal I 1000km Ishikawa et al. (2008) Chromospheric reconnection produces high-frequency waves log period 5min 10s Wavelet spectrum of Vx in corona Wavelet spectrum of Vx in photosphere Isobe, Proctor & Weiss (2008) Is fast reconnection possible in chromosphere? Fast reconnection: V reconnection 0.1V Alfven (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 = V A L/ 10 5 Classical Sweet-Parker reconnection seems too slow (e.g., Chae et al. 2002) Hall or ambipolar effects? Hall and Ambipolar effects Induction equation of weakly ionized plasma Hall term (Ion-electron) Ambipolar term (Ion-neutral) Ambipolar/Hall = ci / in ci : Ion-cyclotron freq B in : 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. When Hall/Ambipolar become significant Hall > Advection => 0.1 1 s in photosphere Ambipolar > Advection => 0.1 1 s in chromosphere Length scale tV na = c/ pi (n n /n i ) 1/2 1-10km ( c/ pi : inertia length) => Detection more likely in temporal variation * Possibly important in local dynamo, too (Krishan & Gangadhara 2008) MHD+ambipolar reconnection (Isobe, Krishan & Shibata in prep) Resistive onlyResistive + ambipolar Ambipolar effect sharpens the current sheet (Chitre & Krishan 2001) Enhance the reconnection rate Create smaller plasmoids => higher frequency wave Coordinated observation of Hinode and CaH/K spectroscopy at Hida observatory 60cm Domeless Solar Telescope (DST) at Hida Observatory, Kyoto Univ. Chromospheric response to umbral dots (H. Watanabe et al.) SOT/CaH 2007 Aug 08 high chromosphere photosphere red shift red shifted blue shifted umbral dot dark umbra Bisector analysys => LOS velocity at different heights CaH Wavelength (A) Ellerman bomb (Hashimoto et al.) 10 SOT/Ca H SMART/H, 2007/08/10 SOT/CaHSOT/StokesV Reconnection modified by chromo. oscillation? 11 DST Ca II H spectra Time Blue enhancement Red enhancement target 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) Isobe, Tripathi & Archontis (2007) 2min Hashimoto et al. SOT/Ca II H Hida/DST Spectroheliogram Ca II h 3 0.5 : Fitted profile calculated with MULTI-code * : Observed profiles CaH line profile Jet Quiet region Chromospheric jets (S. Ueno et al.) Shibata et al. 2007 Fitting by MULTI => atmospheric structure upward downward Doppler Velocity Reconnection Point ? 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 Jet-like feature in QS Velocity downward (at the footpoint) throughout photosphere. Reconnection point above? No enhancement in temperature and density Ca II H / h 2 Hida/DST Doppler Velocity upward downward Reconnection Point ? At the bright point at the footpoint of jet. Alfvenic/Okamotic waves in prominence SOT/CaH Pseudo-SOT from DST disk prominence SOT/BFI Isobe et al. Doppler velocity Intensity Black (red) lines trace the peaks/valleys in Doppler velocity (intensity). Phase velocity of Doppler V = km/s No corresponding phase shift in intensity => imcompressible waves time 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, ) temporal resolution