-Short Talk-

1

• -Short Talk-
• The soft X-ray characteristics of solar flares,
  both with and without associated CMEs
• Kay H.R.M., Harra L.K., Matthews S.A., Culhane
  J.L., Green L.M., 2003, AA, 400, 779
• July 14, 2003, Yu Liu

2
Introduction

• Complex relationship between flares and CMEs is
  not clear case studies, statistical studies
• SXR statistical investigation a close
  relationship between temperature, emission
  measure, duration and peak intensity (Harrison
  1995, Feldman et al. 1995, 1996, Aschwanden 1999,
  Veronig et al. 2002), however, they do not
  differentiate between flares with and without
  CMEs

3
Purpose of this work

• To investigate the relationship between flares
  and CMEs using a comparison of flare parameters.
• With data from
• GOES SXR
• LASCO (range of 1.1-32 solar radii)
• EIT (dimming signatures of CME lower in the
  corona)

4
Flares selected (69 samples)

• Both with and without CMEs
• GOES Class B to X
• Duration gt 3min
• simple events were included
• long duration flares with minor events during the
  decay phase were not excluded
• unambiguous determination of whether or not there
  was an associated CME

5

• Flare parameters
• 1.peak intensity
• 2.duration
• 3.peak temperature
• 4.emission measure
• 5.EIT wave

peak intensity
1-8 Å
0.5-4 Å
duration
Fig. 1
6
Detection of a CME

• LASCO
• EIT (FeXII 195A, dimming)
• If insufficient EIT data available, then compare
  EIT images before and after the event to examine
  field opening. Only those appeared without no CME
  were included

7
Results
Table 1. mean temperature and flare durations
Table 2. Mean flare duration and peak temperature
8

• Table 3. Upper and lower limits of SXR flare
  characteristics

9

• Figure 2. peak intensity vs. duration (69 flares)

10

• Figure 3. Peak temperature vs. peak emission
  measure

11

• Figure 4. Peak temperature vs. peak intensity

12

• Figure 5. Rise time vs decay time

13

• Figure 6. Rise time vs peak temperature

14
Discussion

• How to understand the differences between flares
  with and without CMEs
• For a given peak intensity, flares with CMEs
  appear to reach lower peak temperatures,
  suggesting CMEs play the role to remove some
  energy from the region, so less energy to heat
  the plasma
• For a given peak temperature, flares with CMEs
  have higher values for the peak emission measure
  , suggesting a longer time is required to heat
  the plasma to the give peak temperature
• No correlation between peak intensity and
  duration for flares with CMEs, while a clear
  correlation for those without CMEs, suggesting
  CMEs can affect the timescale for energy release
  and cooling within the flares

15
Conclusion

1. Clear correlation between peak intensity and
   duration for flares without CMEs
2. Same correlation between peak temperature and
   peak emission measure for these two classes of
   flares
3. No difference relationship between rise and decay
   time
4. No relationship between the flare rise time and
   the peak temperature, suggesting
5. EIT waves have no correlation between those
   parameters

16
Further work

• To make more complete comparison, we should base
  on more samples and more wavelengths observations
• We will study the HXR properties and non-thermal
  velocities, using data from Yohkoh
• We will make detailed analysis of EIT and TRACE
  images, because magnetic field morphology may
  play an important role for a CME occurrence