Flare Ribbon Expansion and Energy Release Ayumi ASAI Kwasan and Hida Observatories, Kyoto University...
-
Upload
job-sutton -
Category
Documents
-
view
217 -
download
0
Transcript of Flare Ribbon Expansion and Energy Release Ayumi ASAI Kwasan and Hida Observatories, Kyoto University...
Flare Ribbon Expansion and Energy ReleaseAyumi ASAI
Kwasan and Hida Observatories, Kyoto University
Explosive Phenomena in Magnetized Plasma – New Development of Reconnection Research –
March 17 – 19, 2004 @Kyoto
1. INTRODUCTIONMagnetic reconnection mechanism is a key process for the energy release and the particle acceleration during solar flares. We estimated the amount of the
released energy quantitatively, based on the magnetic reconnection model and by using observable values.
We estimate the energy release rate, by using the separation speeds of two ribbons and the photospheric magneti
c field strengths. The estimated reconnection rate and the Poynting flux along each slit show good correlation with the nonthermal
bursts (Fig. 5). They are also locally large enough at the HXR sources, and can explain the difference of spatial distributions betw
een HXR and H images. For more accurate estimation, we have to take into account the relation bet
ween Bc and Bp
Fig.2 H image overlaid with HXR contour image
HXR sourcesstrong energy release
AvBdtdE
ic
4
2
2. ENERGY RELEASE RATE
Fig1. Hfull disk image obtained with Flare Monitoring Telescope at Hida Obs.
NOAA 9415
Energy release rate (dE/dt) is written as: Bc : coronal magnetic field strength vi : in flow velocity A : area of reconnection region
3. RESULTS
The dynamic range of HXT is about10. Therefore, if the released energy at the HXR sources are (at least) 10 times larger than
those at the other H kernels, the difference of appearance can be explained.
Fig.3 Cartoon of magnetic reconnection
Slits were put in the direction of the flare ribbon separation, and calculated Bpvf and
Bp2vf at the outer edges of fla
re ribbons.We followed the temporal ev
olutions of these values.
Fig.5 Time profiles of microwave (NoRH 17GHz), HXR (Yohkoh/HXT), reconnection rate (Bpvf), and Poynting flux (Bp2vf) for slit I (05:
19 UT burst) and slit II (05:26 UT burst).
Qualitatively, both of the estimated reconnection rates (Bpvf) and Poynting fluxes (Bp
2vf) reconstruct peaks of the light curves of the nonthermal emissions.
We made extensive use of Yohkoh Data Center, and SOHO MDI Data Service.
Bcvi = Bpvf
Bc2vi ∝ Bp
2vf
Reconnection rate
Poynting Flux
(conservation of magnetic flux)
(Bc B∝ p is assumed)
The difference of the spatial distributions are
caused by the difference of released
energy!?
Comparing the H images with the HXR images (Fig 2.), we found the difference between the spatial distribution of the H
kernels and that of the HXR sources: only two sources, which are accompanied by the H kernels, are seen in the HXR image.
Sartorius telescope @Kwasan Obs.
Flare (Fig 1.)April 10, 2001 05:00UTNOAA 9415GOES X2.3DataH…Kwasan Obs., Sartorius Tele.Magnetogram…SOHO / MDIhard-X ray (HXR)…Yohkoh / HXTMicrowave…NoRH
Here, we estimate the reconnection rate Bpvf, and the Poynting flux Bp
2vf along the slits which pass the HXR sources, as the parameters of the energy release rates.
Bpvf
neutral line
other Ha kernelsweak energy release
Although it is very difficult to estimate corona physical values (Bc, vi), assuming the conservation law of magnetic flux, and using observable values (Bp, vf ), we estimate
the energy release rate.conservation of magnetic flux fpic vBvB flare ribbon
Bc : coronal magnetic field strengthvf : speed of ribbon separation
Fig.4 Method of the analyses
reconnected loop
microwave
HXR
reconnection rate
Poynting flux
HXR burst at 05:19 UT
microwave
HXR
reconnection rate
Poynting flux
4. SUMMARY
slit I slit II
HXR burst at 05:26 UT
slit I slit II
slit
Quantitatively, both of the reconnection rates and Poynting fluxes are enhanced enough
(more than 10 times larger) at the HXR sources, compared
with those at the other H kernels.
Table 1 Comparison of the reconnection rates and the Poynting fluxes between the H kernels with HXR sources and those without ones
reconnection rate (ratio) Bpvf [V m-1]
Poynting flux (ratio)vfBp
2 [erg cm-2 s-1]
K1 2.6×102 (0.52) 1.3×109 (0.27)K2 7.7×103 (16) 7.6×1011 (150)K3 4.9×102 (1.0) 5.0×109 (1.0)
K3
K1K2
K2 : HXR sources
P1