Introduction to Solar EUV Emission Line Imaging Spectroscopy

CDS CDAW during 4-7 February 2004

Solar EUV Emission Line Imaging Spectroscopy

Tetsuya Watanabe 　（ NAOJ)

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 (overlappogr

aph)

4. 速度診断 (Velocity Diagnostics)Combining both? 5. Non (Ionization) Equilibrium







太陽外層大気の一次元モデル

CIV 1550Å




Spectroscopic Solar AtmospheresPhotosphere; radiative transfer (LTE)

continuum, weak (photospheric) lines absorption → optically thinChromosphere; 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 equilibriumall lines → optically thin, emission lines

--------------------------Optical depth; “optically thin”

CIVλ1548Å: τ0 ~ 10-2

→ 　 Statistical Equilibrium (collisional-radiative model) el

ioneel

D

n

nnAn

fmc

elnLl

8.0

1 ;

2/1

2

000




連続光の opacity




SXV 5.04Å

Solar transition region &corona

SUMER spectra Yohkoh/BCS




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)




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




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




Ionization Equilibrium; Relaxation Time Scales

Brooks et al. (1999)

Neτequil ~ 1012 cm-3sec




Line intensity of a permitted line (j → i)

)exp(

)()(

)(

)(

)(

)(

)(

)(

)(

)(

)(

2

02

16

1063.8 kTE

aTC

XNNC

XNCNNA

NNHN

HNXN

XNXN

XNXN

N

NA

e

ij

i

ij

eij

m

eijij

ij

m

ijejji

ee

m

m

m

j

j

jjiij

ij

hc

hc

←radiative-collisional model

excited state << ground state

(Emissivity /volume)




factorGaunt ; strength oscillator ;

potential ionizationhydrogen ;

3

8

energyelectron incident ; radiusBohr ;

)()(/

strengthcollision ; weight lstatistica ;

ij

20

wellmax

22

0

0

gf

I

Ka

vdvvfvnnCnn

ij

H

ijiij

H

i

v

ijieijieii

ij

ij

iji

fgEI

Ka




TkTE

XNXN

TG

NHN

HNXNhc

NTG

e

eij

m

ei

ij

ij

eij

2/1

6

2

)/exp()()(

)(

)()()(

1063.8

)(

G(T); contribution function

↑ ion fraction

↓element abundance




dTTTG

dSdTT

NTG

dTTdVNTdh

dTdSdhdV

dVNTG

dVNTGI

e

e

em

e

)()(

1)(

)(

l)(isotherma )(

)(

2

2

2

2

←　 differential emission measure

← emission measure




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

]/)(exp[)(

)(eikij

ij

ik

ik

ij

ik

ij kTEE




SXVI

SXV

SXIV

1s

1s22s 1s22p

1S 1s2

1s2s2p1s2p2

3S 1s2s1P 1s2p3P 1s2p

q

q

j, k

j, k

z

z

x

y

x, y

w

w

(Li-like)

(He-like)




SXV temperatature diagnostics w




Temperature Sensitive Line Pairs (CDSn,g/SUMER)

ION Wavelength (λ) OIII 702.98g/599.59nOV 172.17g/629.73nOVI 184g/1032sNeV 359n/572.20n 365n/572.20n

416.20g/569.20n or 572.20nMgIX 705.80g/749gSiXI 604n/580.90n




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)







Density diagnostics ← collisional deexcitation ~ radiative decay

1. Allowed line excited from the ground statevs.

2a. Forbidden line originating from metastable levels

2b. Allowed lines excited from metastable levels




Helium-like ion

resonance line (w) ; 1s2 1S – 1s2p 1P

forbidden line (z); 1s2 1S – 1s2s 3S

intersystem line (x,y); 1s2 1S – 1s2p 3P




SXVI

SXV

SXIV

1s

1s22s 1s22p

1S 1s2

1s2s2p1s2p2

3S 1s2s1P 1s2p3P 1s2p

q

q

j, k

j, k

z

z

x

y

x, y

w

w

(He-like)




SXV density diagnostics

Te = 9×106 K




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)

4

3

2

1

C13 A31 A32

C14 <<C13~C24

C14 C24 A42 C23

C12C21 A21




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 A≒ 21; density sensitive)

~ const for high density (n2/n1 ~ const)




FeXIV density sensitive line ratio

λ 274.21Å 3s23p 2P1/2 (1) – 3s3p2 2S1/2 (3)

λ 264.79Å 3s23p 2P3/2 (2) – 3s3p2 2P3/2 (4)λ5303Å




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




Line profile (intrinsic)

Voigt (Gaussian + Lorenzian)

Gaussian

thermal Doppler (+ microturbulence)Lorenzian

natural damping

Others

pressure (van der Waals) broadening

Stark broadening (Holtsmark)




Overlappograph

凹面回折格子

dvvvxixI )()()( 　

Slitless emission line spectroscopy







Velocity (line of sight velocity) diagnosticsMicroturbulence correlation length …smallMacroturbulence; correlation length …small (transverse) …long (line of sight)Systematic motion (blue/red shifts) correlation length…long

2/120 )2

( m

kT

cD

000 )()()()( dviI 　

i

iic vvII )()( ,




Strong & isolated lines for dynamic studies(CDS/NIS)

Ion 　　 Wavelength(Å) log THeI 584.33 4.3OIII 599.59 4.9OIV 554.52 5.3NeVI 562.83 5.6MgVIII 313.73 5.9MgIX 368.06 6.0FeXII 364.47 6.2FeXIII 320.80 6.2FeXIV 334.17 6.3FeXV 327.02 6.3FeXVI 335.40 6.4




s

BeH

H

elem

elem

ion

ion

l

iiiiiiieii

dsEI

T

TkW

NNN

N

N

N

N

NhcE

SNSNNNs

vN

t

N

0

1111

)()exp(

))(()(

Non-Equilibrium




Dynamic Transition Region and Corona (CDS)




12

1

)()(

,)()()(

,0)(

2

2

pvEwhere

SLsvgs

TvpE

st

E

s

psg

s

v

t

vs

v

t

Hydrodynamical Simulations (Teriaca et al. 1999)

Nano flare at the OVI forming layer




References:Mariska J. T.: Solar Transition Region, 1992,

Cambridge University Press.Jefferies, J. T.: Spectral Line Formation, 196

8, Blaisdell Publ. Co.Harrison, R. A. & Fludra, A.: CDS for SoHO

Scientific Report, 199x, RAL SUMER Red Book; 199y, Max-Planck Institu

te für Aeronomie

Documents

Introduction to Solar EUV Emission Line Imaging Spectroscopy