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Introduction to Solar EUV Emission Line Imaging Spectroscopy

Introduction to Solar EUV Emission Line Imaging Spectroscopy. 国立天文台 渡 邊 鉄 哉. 目次 1a. Coronal Condition と輻射・衝突モデル 1b. Ionization Equilibrium Line Intensity 2. 温度診断 (Temperature Diagnostics) 3. 密度診断 (Density Diagnostics) Line Profile 1c. 　スリットレス・輝線撮像分光 (overlappograph)

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Introduction to Solar EUV Emission Line Imaging Spectroscopy

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  1. Introduction to Solar EUV Emission Line Imaging Spectroscopy 国立天文台 渡 邊 鉄 哉

  2. 目次 • 1a. Coronal Conditionと輻射・衝突モデル • 1b. Ionization Equilibrium • Line Intensity • 2. 温度診断 (Temperature Diagnostics) • 3. 密度診断 (Density Diagnostics) • Line Profile • 1c.　スリットレス・輝線撮像分光 (overlappograph) • 4. 速度診断 (Velocity Diagnostics) • Combining both? • 5. Non (Ionization) Equilibrium

  3. 太陽外層大気の一次元モデル CIV 1550Å

  4. Spectroscopic Solar Atmospheres • Photosphere; radiative transfer (LTE) • continuum, weak (photospheric) lines absorption → optically thin • Chromosphere; radiative transfer (non-LTE) • strong (chromospheric) lines (NaID, CaIIH&K, MgIIh&k, HIC=Hα, CI/II, Lyα...) → optically thin, temperature inversion → emission lines • Transitioin region/Corona; statistical equilibrium • all lines → optically thin, emission lines • -------------------------- • Optical depth; “optically thin” • CIVλ1548Å: τ0 ~ 10-2 • →Statistical Equilibrium • (collisional-radiative model)

  5. 連続光のopacity

  6. Yohkoh/BCS SUMER spectra SXV 5.04Å Solar transition region &corona

  7. Statistical Equilibrium → collisional-radiative model • dni/dt = (∫j + Σj) Pijni - (∫j + Σj) Pjinj ~ 0 • (∫j + Σj) nj = N (N; total no. of particles) • Pij = Cij + Rij Pji = Cji + Rji • Coronal Condition • ○Collisional excitation – Radiative decay • ○Collisional (auto) ionization • – Radiative (dielectronic) recombination • →Pij~ Cij Pji ~ Rji (+Cji)

  8. Coronal Condition • Rate (cm-3s-1) Characteristic time (s) opt.thin low n • Collisional excitation nineCij 2×10-3 • Radiative excitation (absorption) niBij4πJ × • Collisional deexcitation nj*neCji 2×10-3× • Spontaneous radiative decay njAji 4×10-9 • Collisional ionization nenionqcoll 107 • Autoionization nenionqauto • Phtoionization nionαrad4πJ × • Total ionization nenionqtot 107 • Radiative recombination nenionαrad 88 • Dielectronic recombination nenionαdiel • Three-body recombination (collisional recombination) × • Total recombination rate nenionαtot 88

  9. Dielectronic recombination/Autoionization • X+z(nl) + e (E, l”+1)↔ X+(z-1)(n’l+1; n”l”) • X+(z-1)(n’l+1; n”l”) → X+(z-1)(nl; n”l”) + hν • ← X+(z-1)(nl; n”l”) + e

  10. Ionization Equilibrium; Relaxation Time Scales Neτequil ~ 1012 cm-3sec Brooks et al. (1999)

  11. Line intensity of a permitted line (j → i) (Emissivity /volume) ←radiative-collisional model excited state << ground state

  12. ↓element abundance ↑ion fraction G(T); contribution function

  13. ←emission measure ←differential emission measure

  14. Temperature diagnostics • 　← Intensity ratio of two permitted lines at the same ionization stage • Li-like; (2s-3p, 2s-3s, 2p-3d) / (2s-2p) • OVI, NeVIII, MgX, … • He-like; Gabriel (1972) • resonance/dielectronic satellites • inner-shell excitation lines

  15. j, k w SXVI 1s z SXV 1P 1s2p x, y 3S 1s2s 3P 1s2p q 1s2p2 1s2s2p x y j, k q z w 1S 1s2 SXIV 1s22s 1s22p (He-like) (Li-like)

  16. w • SXV temperatature diagnostics

  17. Temperature Sensitive Line Pairs (CDSn,g/SUMER) • ION Wavelength (λ) • OIII 702.98g/599.59n • OV 172.17g/629.73n • OVI 184g/1032s • NeV 359n/572.20n 365n/572.20n • 416.20g/569.20n or 572.20n • MgIX 705.80g/749g • SiXI 604n/580.90n

  18. Differential Emission Measure • FeVIII(log T=5.6), IX, X, XI, XII, XIII, XIV, XV, XV, XVI, XVII (log T=6.5) • MgVI(log T=5.6), VII, VIII, IX (log T=6.0) • SiVII(log T=5.8), VIII, IX, X (log T=6.0) • NeV (log T=5.5), VI, VII, VIII (log T=5.8) • NeI (log T=4.4), III (log T=4.9)

  19. Density diagnostics • ← collisional deexcitation ~ radiative decay • Allowed line excited from the ground state • vs. • 2a. Forbidden line originating from metastable levels • 2b. Allowed lines excited from metastable levels

  20. Helium-like ion • resonance line (w) ; 1s21S – 1s2p 1P • forbidden line (z); 1s21S – 1s2s 3S • intersystem line (x,y); 1s21S – 1s2p 3P

  21. j, k w SXVI 1s z SXV 1P 1s2p x, y 3S 1s2s 3P 1s2p q 1s2p2 1s2s2p x y j, k q z w 1S 1s2 SXIV 1s22s 1s22p (He-like)

  22. SXV density diagnostics • Te = 9×106 K

  23. C14 <<C13~C24 4 3 2 1 A31 C13 A32 C14 C24 A42 C23 C21 A21 C12 • Four level case • R=(n4A42)/(n3A31) • n4(A42+A41)=n1neC14+n2neC24 • n3(A32+A31)=n1neC13+n2neC23 • n1ne(C12+C13+C14)=n4A41+n3A31+n2(A21+neC21)

  24. αji≡Aji/(Aj1+Aj2) • R={α42[C14+(n2/n1)C24]}/{α31[C13+(n2/n1)C23]} • n2/n1=(C12+C13α32+C14α42)/ • (A21/ne+C21+C23α31+C24α41) • ∴ R = (α42C14)/(α31C13) for low density (n2/n1 << 1) • (neC12 ≒ A21;density sensitive) • ~ const for high density (n2/n1 ~ const)

  25. FeXIV density sensitive line ratio λ 274.21Å 3s23p 2P1/2 (1) – 3s3p22S1/2 (3) λ 264.79Å 3s23p 2P3/2 (2) – 3s3p22P3/2 (4) λ5303Å

  26. Iron ion density sensitive line pairs (CDS) • Ion Wavelength (λ) • FeX 175.27/174.53g • FeXI 180.41,184.70/181.14g • FeXII 186.87,196.64/193.51g • 338.27/364.47n • FeXIII 202.04, 201.12/200.02g, 203.79g • 318.12, 348.18/320.80,359.64n • FeXIV 219.12/211.32g • 264.80/274.20g

  27. Line profile (intrinsic) • Voigt (Gaussian + Lorenzian) • Gaussian • thermal Doppler (+ microturbulence) • Lorenzian • natural damping • Others • pressure (van der Waals) broadening • Stark broadening (Holtsmark)

  28. Slitless emission line spectroscopy Overlappograph 凹面回折格子

  29. Velocity (line of sight velocity) diagnostics • Microturbulence • correlation length • …small • Macroturbulence; • correlation length • …small (transverse) • …long (line of sight) • Systematic motion • (blue/red shifts) • correlation length…long

  30. Strong & isolated lines for dynamic studies • (CDS/NIS) • Ion Wavelength(Å) log T • HeI 584.33 4.3 • OIII 599.59 4.9 • OIV 554.52 5.3 • NeVI 562.83 5.6 • MgVIII 313.73 5.9 • MgIX 368.06 6.0 • FeXII 364.47 6.2 • FeXIII 320.80 6.2 • FeXIV 334.17 6.3 • FeXV 327.02 6.3 • FeXVI 335.40 6.4

  31. Non-Equilibrium

  32. Dynamic Transition Region and Corona (CDS)

  33. Hydrodynamical Simulations (Teriaca et al. 1999) Nano flare at the OVI forming layer

  34. References: • Mariska J. T.: Solar Transition Region, 1992, Cambridge University Press. • Jefferies, J. T.: Spectral Line Formation, 1968, Blaisdell Publ. Co. • Harrison, R. A. & Fludra, A.: CDS for SoHO Scientific Report, 199x, RAL • SUMER Red Book; 199y, Max-Planck Institute für Aeronomie

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