Evolution of H Flare Kernels and Energy Release

Ayumi ASAI

Nobeyama Solar Radio Observatory, NAOJ

6th Solar-B Science MeetingNovember 11, 2005 @Kyoto

2001-Apr-10 flare (Hida Obs.)

What can we learn from Flare Kernels/Ribbons?

magnetic reconnection(Carmichael 1964; Sturrock 1966; Hirayama 1974; Kopp-Pneuman 1976)

Evolution of flare ribbons Information on Magnetic reconnection

　 chromoshere

corona

What can we learn from Flare Kernels/Ribbons?

• Precipitation of accelerated particles into the chromosphere

HXR emissions and H kernels

Precipitation of nonthermal particles

HXR

bremsstrahlung rapid thermalization

H kernel

H kernels Information on particle acceleration

What kind of information, and how, we can derive from the Ha observations on flare ribbons and kernels?

simultaneously brighten

• Nonthermal particles and thermal conduction bombard the chromospheric plasma at both the footpoints simultaneously

The temporal evolutions of the footpoints are similar to each other

• We identify the conjugated pairs of the footpoints which show similar light curves

N S

?

1. Conjugacy of H Footpoints

red:positive, blue:negative

Asai et al. 2003

Movement of the site of energy release

t

Focus on Each Pair

2. Energy Release Rate

• estimate of the amount of the released energy, by using observable values to test the reconnection model

• compare the derived energy release rate with HXR/microwave light curves

AvB

dt

dEW in

c

42

2

Reconnection model indicatesAsai et al. 2004

microIIW HXR

Empirically, it is said that

Electric Field

fpinc vBvBE

Energy Release Rate

conservation of magnetic flux

Poynting Flux

fpinc vBvBW 22 I estimate the energy release rate, by using observable values (Bp, vf)

H flare ribbons

Bc

Bp

microwave

HXR

reconnection rate

Poynting flux

An HXR burst occurred on the slit (05:19 UT).

Reconnection Rate and Poynting Flux

B vB2 v

microwave

HXR

reconnection rate

Poynting flux

An HXR burst occurred on the slit (05:26 UT).

Reconnection Rate and Poynting Flux

H image

HXR sourcesflare ribbons

HXR/microwave Emission

Energy Release Rate

microIIW HXR

Quantitative Estimation

E4

E3

E1

W4

W3E2W2

W1 Comparison of Poynting and Electric Field (Reconnection Rate) between the H kernels with HXR sources and those without ones

E2W2

• H line is shifted red-ward red-asymmetry• velocity : 50-100 km/s

H

H spectrumIchimoto & Kurokawa 1984

flare

chromosphere

corona

compression

X-ray

H line

3. H Kernel Spectroscopy

Red-Asymmetry Map

2/)( bluered

bluered

II

II

map

2/)( bluered

bluered

II

II

• H +1.5A, -1.5A• we calculated 　　　　

　　　　　　　　　

　　　　　　　 as an indicator of r.a.

• all over the flare ribbon, the tendency of r.a. is seen

Scatter Plot (intensity vs RA)in

tens

ity o

f H

ker

nel

redbluestrong asymmetry @outer edges of the flare ribbon2/)( bluered

bluered

II

II

The downflow velocity is roughly about 30 km/s.

Red Asymmetry

Summary

• We can learn from H flare kernels/ 　 ribbons:

• Site and timing of energy release by identifying conjugated footpoints

• Energy release rate, by using the separation motions of two ribbons and the photospheric magnetic field strengths

• Dynamics at the footpoints by the red-asymmetry distribution

Thank you!