Solar Flares - Hinode Perspec.ve -

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1 Solar Flares - Hinode Perspec.ve - EIS SOT XRT Coupling and Dynamics of the Solar Atmosphere 2014 Nov 10 Pune, India Hirohisa Hara NAOJ

2 Solar Flare Research by Hinode Solar flares: explosive events on the Sun that produce >10MK plasmas and high- energy par.cles by hea.ng and par.cle- accelera.on processes. Research Topics Energy storage and trigger processes Par.cle accelera.on and chromospheric evapora.on Magne.c reconnec.on Unique Approach by Hinode (SOT + XRT +EIS ) High- resolu.on; especially SOT sub- arcsec imaging Photo. vector B field (imaging & spectro- polarimetry) High- cadence X- ray imaging EUV scanning spectroscopy Limited capability

3 sx

4 Microflares Magne.c Connec.vity & Morphology Kano et al. (2010) XRT + SOT

5 Onset Problem of Solar Erup.ons Various models have been proposed to explain the onset of solar erup.ons. strong magne.c shear (Low 1977, Mikic & Linker 1994) reversed shear (Kusano et al. 2004) sigmoid & kinking (Rust & Kumar 1996, Canfield et al. 1999, Moore et al. 2001, Kliem et al. 2004) emerging fluxes (Heyvaerts et al. 1977; Wallace et al. 2010) flux cancella.on (van Ballegooijen & Martens 1989, Amari 1999, 2000, Green et al. 2011) Loss- of- equilibrium model (Priest & Forbes 2002) Breaqkout in mul.polar topologies (An.ochos et al. 1999, Sterling & Moore 2004) sharp gradient of B (Schrijver 2007)

6 Hinode Flare

7 Stability of Ac.ve Region Inoue, Kusano et al. ApJ 2011 Hinode/SOT Vector Magnetogram NLFFF T n Magne.c Twist = (4 π ) 1 field line α dl Smaller than threshold Magne.c field at 20:30UT on Dec.12, 2006 Flare onset at 02:12UT on Dec.13, 2006

8 Ensemble Simula.on Study strong shear weak shear non- poten.al Parameter Space Kusano+2012 magne.c shear angle poten.al poten.al field Right Polarity azimuth angle of small magne.c disturbance Opposite Polarity Right Polarity Normal Shear Reversed Shear

9 Simula.on Results Flare phase diagram (Kusano et al. 2012) strong shear weak shear no flare 2- ribbon flare Compact Flare flare Failed Erup.on no flare magne.c shear angle Jet poten.al field Right Polarity Opposite Polarity OP RS Kine.c Energy Normal Shear Reversed Shear

10 Observa.onal Evidence Simula.on (flare phase diagram) Observa.on (Hinode) Bamba et al AR10930 X3.4 AR10930 X1.5 AR11158 M6.6 AR11158 X2.2

11 Chromospheric evapora.on Non- thermal thick- target model Thermal model From Fisher (1986)

12 eeuv imaging spectrograph Solar North SOHO λ Raster scan Hinode SUMER Solar South Sun EIS t 32 t 20 time t 10 t 1 Example of Raster scan image Slit of both spectrographs is oriented in the north- south direc.on.

13 Chromospheric Evaporation studied by plenty of EUV spectral lines Mostly studied from EIS data. T e dependent flow speed Milligan & Dennis (2009) Watanabe et al. (2010) Chen & Ding (2010) Li & Ding (2010) Doppler velocity V D (km/s) Milligan & Dennis 2009, ApJ, 699, 968 High density at the footpoints from density sensitive line ratio Fe XIII-XIV: cm -3 (Watanabe et al. 2010) Fe XII-XIV: cm -3 (Milligan 2011) Fe XIV : cm -3 (Del Zanna et al. 2011) High-density kernels are in a narrow layer 200km Fe XIII : cm -3 (Graham et al. 2011) Accelerated electron injec.on Te (K)

14 Non- thermal broadening SMM/BCS: Antonucci et al. (1982) Gradual phase HXRBS: Hard X- rays kev T (MK) T i I Ca XIX T e λ V D : -340km/s upflow Impulsive phase T (MK) 50 T i I Fe XXV 30 T e Solid: two component finng Dashed: a single component finng 10 V D : -389km/s upflow 9:15 9:19 9:23 9:27 Time (UT)

15 Non- thermal Velocity in Flares Site of non- thermal velocity observed in flaring loops and its size has not been understood. W obs : observed FWHM of an emission line Yohkoh BCS observa.ons No spa.al resolu.on V NT (km/s) From Mariska and McTiernan 1999, ApJ, 514, Occulted flare by the disk at the limb

16 V NT at the footpoints from Non- thermal broadening of emission lines at Flare Kernel V NT (km/s) Milligan (2011), Young et al. (2013) O VI Mg VI Mg VII Fe VIII Fe X Fe XI Fe XII Fe XIII Fe X IV Fe XV Fe XVI Fe XVII * * He II * * Mul.ple component finng * * * * * Fe XXIII Fe XXIV 1 3 MK range: Milligan (2011): unresolved flow structures, turbulence (?) Young+ (2013): mul.ple flow component (upflow and downflow simultaneously detected )

17 V NT at/above the loop tops Impulsive phase: V NT = km/s Hara et al. (2011, 2014) Kawate & Imada (2013) Peak to late phase: V NT = km/s Hara et al. (2008) Doschek et al. (2014) Fe XXIV 255 V NT ( km/s ) Late Phase of an X- class Flare Box No. Hara et al. (2008) Doschek et al. (2014)

18 Line broadening at the loop top AIA 131(Fe VIII, Fe XXI) 4-6 kev kev 13:33:50-13:39:36 - a side view Symmetric line profile with enhanced line broadening EIS: Fe XXIII line intensity X-ray Flux (W m -2 ) 13:39:39-13:45:25 13:45:28-13:51:15 13:51:18-13:57: :20 13:30 13:40 13:50 14:00 14:10 14:20 Start Time (10-Feb-11 13:20:00) arcsec arcsec arcsec arcsec T e ~ 11MK T i ~ 50 MK (or V NT ~ 110 km/s) T e ~ 11 MK T i ~ 20 MK (or V NT ~ 40 km/s) T e ~ 14MK T i ~ 45 MK (or V NT ~ 100 km/s) T e ~ 12 MK T i ~ 20 MK (or V NT ~ 40 km/s) Hara+ (2014)

19 Magnetic Reconnection: a model based on Yohkoh imaging observations Topics inves.gated by spectroscopy to understand magne.c reconnec.on processes in the solar atmosphere. - Reconnec.on inflow - Reconnec.on ourlow/plasmoid - Posi.on of enhanced hot line broadening found in 1970s - MHD Shock Shibata et al. (1995)

20 Observed & Suggested Structures in 2007 May 19 Flare (GOES B9.5) Hara+2011, ApJ, 741, 107

21 Reconnec.on Inflow

22 EUV Imaging Observa.ons: Reconnec.on Inflow B Time- distance diagram Time B A Space A SOHO/EIT Observa.on Yokoyama et al. (2001) Yokoyama et al. (2001) Es.ma.on of inflow speed from apparent mo.on of coronal structures around a flare V inflow ~ 5 km/s, M A =V inflow /V A = (uncertainty in V A ) Narukage & Shibata (2006); 6 events V inflow = 2 14 km/s, M A =V inflow /V A =

23 First Spectroscopic Observa.on of t = t 1 t = t 2 Reconnec.on Inflow Fe XII λ195 H α Intensity Doppler 1 Difference of EUV images Fe X 6374 observa.on at Norikura Solar Observatory of NAOJ (λ/δλ=1e5) [ Hara et al. 2006, ApJ, 648, 728 ] V D, inflow ~ 3 km/s [observation] M A ~ when V A ~ 1000 km/s in the corona [ assumption in B ] Time (UT)

24 EIS Spectroscopic Observa.ons: - Reconnec.on Inflow in an erup.ve event - EIS Fe XII 195 V D : ~ 3 5 km/s GOES C2.1 Blue Red Doppler velocity [km/s] - Weak Doppler signature of inflow - No mul.ple observa.ons to prove - No 10 7 K line observa.ons

25 Magne.c Reconnec.on in an erup.ve event GOES B9.5 N Inflow Ourlow Line- of- sight from Hinode X- ray flare loop(~ K) W High n e region X- ray Loop 1 arcsec = ~700 km on the Sun

26 Magne.c Reconnec.on in an erup.ve event Fe XII (~1.4 MK) Ourlow Line- of- sight from Hinode Inflow High n e region Line- of- sight velocity (B: blueshix, R: redshix) X- ray Loop 1 arcsec = ~700 km on the Sun Inflow speed: V D ~ 20 km/s

27 Reconnec.on Inflow AIA 131 (10 7 K) (Fe VIII, Fe XX, Fe XXIII) GOES M1.0 Fe IX/X (~1MK) Signature of reconnection inflow structure was observed in AIA171 as a disappearing loop: apparent speed ~50 km/s EIS observed blueshift of -25 km/s and intensity decrease in Fe X 184. M A ~V inflow /V outflow ~ 0.1 Fe X 184 Doppler velocity 04:41:14 04:46:34 04:51:55 V D (km/s) inflow Posi.on along slit (arcsecs)

28 Reconnec.on Ourlow/Plasmoids

29 Yohkoh Imaging Observa.ons: Plasma Ejec.ons T e I Tsuneta (1997) Ohyama & Shibata (1998)

30 Yohkoh Imaging Observa.ons: Plasma Ejec.ons Apparent T e I Tsuneta (1997) Too slow for coronal Alfven speed Ohyama & Shibata (1998)

31 Reported EUV Observa.ons of Reconnec.on Ourlows A few cases have only been reported on the spectrum of reconnec.on ourlow. A dark structure in general. SOHO/SUMER: Innes+2003 (X1.5) Fe XXI Wang+2007 (M2.5) Fe XIX No scanning observa.ons Hinode/EIS: Hara+2011 (B9.5) Fe XXIV, Fe XXIII, Ca XVII Imada+2013 (X1.7) Fe XXIV Innes+2003 (GOES X1.5) Wang+2007 (GOES M2.5) EUV image Fe XXI EUV image Fe XIX Slit Slit λ λ

32 Reported EUV Observa.ons of Reconnec.on Ourlows A few cases have only been reported on the spectrum of reconnec.on ourlow. A dark structure in general. SOHO/SUMER: Innes+2003 (X1.5) Fe XXI Wang+2007 (M2.5) Fe XIX Hinode/EIS: Hara+2011 (B9.5) Fe XXIV, Fe XXIII, Ca XVII Imada+2013 (X1.7) Fe XXIV No scanning observa.ons Innes+2003 (GOES X1.5) Wang+2007 (GOES M2.5) Fe XXI 10 4 wide slit 4 wide slit 50s exp 50s exp Fe XIX red λ red λ

33 Reported EUV Observa.ons of Reconnec.on Ourlows A few cases have only been reported on the spectrum of reconnec.on ourlow. A dark structure in general. SOHO/SUMER: Innes+2003 (X1.5) Fe XXI Wang+2007 (M2.5) Fe XIX Hinode/EIS: Hara+2011 (B9.5) Fe XXIV, Fe XXIII, Ca XVII with scanning observa.ons Hara+2011 (GOES B9.5) Raster scan image Fe XXIII 263 Imada+2013 (X1.7) Fe XXIV Velocity [km/s] Imada+2013 (GOES X1.7) Raster scan image Velocity [km/s] Fe XXIV wide slit 40s exp I (erg cm -2 s -1 sr -1 Å -1 ) Fe XXIV wide slit 5s exp Wavelength [Å] λ Wavelength [Å] λ

34 Magne.c Reconnec.on in an erup.ve event GOES B9.5 N Inflow Ourlow Line- of- sight from Hinode W High n e region X- ray flare loop(~ K) X- ray Loop 1 arcsec = ~700 km on the Sun

35 Magne.c Reconnec.on in an erup.ve event Dura.on of impulsive phase N High n e region Inflow Ourlow Line- of- sight from Hinode W 西 High n e region Raster scan image EUV line intensity (~ K) X- ray Loop 1 arcsec = ~700 km on the Sun High n e region: T e = 12 MK [ Fe XXIV/Fe XXIII, RHESSI continuum] T i = 50 MK (or V NT =100 km/s) [Fe XXIII line width] V D = 30 km/s (downward)

36 Magne.c Reconnec.on in an erup.ve event Count (DN) N W Inflow Ourlow High n e region Line- of- sight from Hinode Raster scan image X- ray Loop 1 arcsec = ~700 km on the Sun Outflow speed: V D = km/s

37 Slow component Fe XXIV 192 Fast component ( V > 200 km/s) Fe XXIV 192 AIA 131 Raster scan image GOES M1.0 Raster scan image EUV image Fe XXIV Fe XXIV erg cm - 2 s- 1 sr - 1 Å - 1 Fast Slow Fe XII Fast Slow Fe XII Broad line profile with a sta.onary component(fwhm~400km/s)

38 Dynamics in an EIS sparse raster GOES X1.2 Many changes are going on during a single EIS raster observa.on. AIA 131 AIA 131 diff.

39 AIA 131

40 EIS Fe XXIV 192

41 EIS Fe XXIV 192 (smoothed)

42 Spectrum in the thin structure above the cusp Doppler Velocity V D (km/s) Ph/bin Fe XXIV Fe XII Redshix component V D = 320km/s EIS Fe XXIV 192 Broad profile with a sta.onary component Shixed component: FWHM=400km/s V NT = 230 km/s (T i =1.0E7 K) or T i = 2.0E8 K

43 Geometry & V outflow STEREO- B / EUVI 195 STEREO- B AIA & EUVI images: 1 / cos θ = Voutflow = V D (320 km/s)/ cos θ = [ km/s ] M outflow = V outflow / V Fast > 1.18 at least Sun SDO SDO / AIA 193

44 Reconnec.on Inflow: Speed: V D = 3 20 km/s v Disappear after entering reconnection region due to heating MR: gain from Hinode Recent EUV spectrograph observa.ons have revealed: Slow & Fast Shock: v Presence suggested from thermal parameters T e, outflow /T e,inflow, n e, outflow /n e, inflow T e, blob /T e,outflow, n e, blob /n e, outflow M A, inflow ~ v An example: V outflow /V fast > ~1.2 Reconnec.on ourlow/plasmoid: Speed: V D = km/s some V ~ V A v Dark structure in general v Broad line profile (turbulence) v with stationary component v Blobby structure, 3D geometry v An example: V outflow /V fast > ~1.2 Improved observa.ons: ~30sec integration is required for pixel-by-pixel investigation using the current instrumentation in Hinode. SOLAR-C Further sensitivity for more rapid and pixel-by-pixel analysis

45 Summary From vector B measurements by Hinode and MHD simula.ons, some promising models for solar flare are appearing. Observa.ons of chromospheric structures and B are crucial. Atmospheric response to the accelerated electrons in solar flares has been inves.gated from high- resolu.on imaging and TR- corona spectroscopy. Flow structures near the site of magne.c reconnec.on have been mapped in the EUV spectroscopy, and the presence of temperature structure in the current sheet may be becoming visible.