The CME-Flare Relationship in Homologous Eruptive Events

Moon, Y.J., Choe, G.S., Wang, H., Park, Y.D., Cheng, C.Z.

2002, Submitted to Ap.J.

2003 Jun. 2 雑誌会

IntroductionZhang et al. (2001), Neupert et al. (2001)

In these studies, it has been demonstrated that the impulsive acceleration phases of the CMEs very well coincide with the rising phases of the associated soft X-ray flares.

Harrison et al. (1985), Harrison (1986) reported that the CME initiation is timed 10 to 20 minutes before the start of HXR flaring.

Kahler et al. (1988) found that the filament eruption began 2-6 minutes before the flare impulsive phase identified by HXR emissions.

Zhang et al (2001), Neupert et al (2001) showed that the acceleration of CMEs are quite coincident with the rise of GOES X-ray fluxes without any extrapolation.

Nitta and Hudson (2001), Zhang and Wang (2002) considered six recurrent flares as homologous flares.

We doubt for following reasons ;

I. CMEs erupting directions are somewhat different from those of the first four events.

II. HXT flare kernels of first four events are different from those of last two.

III. Fifth event does not show any visible expansion or any remotely moving flare ribbons.

Last two eventshave different eruption dynamics and flaring processes from those of first four events.

DATA

CMEs erupting directions are somewhat different from those of the first four events.

HXT kernels of first four events are different from those of last two.

Fifth event does not show any visible expansion or any remotely moving flare ribbons.

Results

We have examined horizontal velocity distributions near the flaring time.

I. The standard deviation of velocity fluctuation is about 0.06 km/s.

II. Expanding motions of leading sunspot are outstanding and flow pattern is quite similar.

The correlation coefficients between the CME speeds and the log peak fluxes are 0.95.

Zhang et al. (2001) shows that correlation coefficients of 0.98 for log peak fluxes vs CME speeds and 0.90 for log peak fluxes vs CME accelerations.

We still do not assert that the statistical results are conclusive since the number of events under consideration are small. However, we can at least say that there may be a closer relationship between flare activities and CME kinematics.

Flare Strength and CME Kinematics

Initial kinematics of an erupting filament

the filament eruption started about 10 minutes before the start time (21:42 UT) and 20 munutes before the strat of HXR brightening. Interestingly, the start time of filament eruption is close to the start time of pre-flare brightening. A larger acceleration is likely to occur near the eruptive phase of GOES X-ray curves, which is consistent with Zhang et al (2001) and Neupert et al. (2001).

Because the growth of eruption speed must have been tamed down, the 5 minutes time difference can be explained.

The outer envelope of an erupting filament can be used as a tracer of CME near the solar surface in its initial evolutionary stage.

To our knowledge, an exponential growth of the filament eruption speed has never been observed.

●What would be the physical meaning of the initial exponential growth of the filament eruption speed?

The fact that it lasts quite a long time excludes a possibility of any linear instability.

The filament eruption can be interpreted as a dynamic response of the magnetic field either to a change in boundary conditions or to a change in field connectivity by preflare reconnection.

Summary and Discussion Our study has revealed that there is a good correlation between the ejection speed of the CMEs and the peak flux of the related flares.

We found that the eruption speed increases almost exponentially with time in the initial phase of the eruption.

A flare is not driver of CME because a filament eruption is initiated at least 10 minutes before the flare onset.

In order explain the good relation, we pay attention to the “plasmoid-induced-reconnection model”.

102070Separation Velocity of Two Ribbons (km/s)

1500050000Initial Distance of Two Ribbons (km)

190350510Plasmoid Velocity (km/s)

no data1000013000HXRS Max. Intensity (CT/S)

301500no dataHXT Max. Intensity (CT/S/SC)

1.22.23.0Rise Time (minutes)

21:4314:5104:55Start Time (UT)

Event IIIEvent IIEvent I

Results

CME velocity (km/s) 711 890 935 610

( Nitta and Hudson 2001) (event IV)