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Study of preflare activity in Yohkoh SXT images

Study of preflare activity in Yohkoh SXT images. Sue Jin Kim 1,2 , Y-J Moon 1 , K-S Kim 2 1. Korea Astronomy and Space Science Institute 2. Kyunghee University. Contents. Introduction Data Statistical study Case study Future plan. Preflare. Introduction.

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Study of preflare activity in Yohkoh SXT images

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  1. Study of preflare activity in Yohkoh SXT images Sue Jin Kim1,2, Y-J Moon1, K-S Kim2 1. Korea Astronomy and Space Science Institute 2. Kyunghee University

  2. Contents • Introduction • Data • Statistical study • Case study • Future plan

  3. Preflare Introduction • Independent energy release and/or initial release of the main flare • Simnett, Harrison (1984) CME launch time ≈ pre-flare time • Ohyama (1997) 1993 C9.7  Pre-flare heating ≈ 11 ± 4MK • Moon et al. (2004) 2000 X1.8  pre-flare brightenings just before the eruption near the footpoint of the filament Connectivity with solar activity

  4. Statistical study • S. J. Tappin (1991) - HXIS on SMM 1980.2.22~11.21 - 80 precursors of 86 samples - One or more soft X-ray precursors 10 to 60 min before the flare • Farnik et al. (1998) - SXT/Yohkoh, oct.1993~oct.1994 - 32 flares  no definite evidence for spatial connection between pre-flare and flare

  5. Motivation • Investigate development of the solar explosive activity by understanding for physical relationship between pre-flare and flare X-ray source. • Statistical study of preflare activity in soft x-ray data • Case study of these activity by comparing with another filtering data  EUV, magnetogram, and Hα so on.

  6. Data (1999/M class) • Yohkoh SXT ٥0.25 ~ 4.0kev (3–60Å) - 5-6 filter ٥Quiet Mode (QT) - t interval > 30s,Flare Mode (FT) - > 2s ٥Partial Frame Image (PFI) during QT mode ٥ pixel r : 2.46″ ~10″, FOV : 2.6′ ~10.6′ • GOES 10 X-ray flux curve ٥ 0.5–4.0Å, 1.0–8.0Å Selection of data Ⅰ. Collect events observed continually before flare start time  20 events Ⅱ. Find X-ray flux enhancement in preflare phase.  10 events = 4 Disk + 6 Limb Examine 4 Disk events.  Statistical study Study the case with other filtering data  Case study

  7. Statistical Study – Spatial relationship 3. Distant 1. Co-spatial 18:21 19:46 1. Co-spatial 2. Adjacent/Overlapping 08:22 07:42

  8. Case study 99 Jan 16 M1.2 • Flaring time 19:50 ~ 20:02 • Pre-flare time 19:46 • AR 8440( E31N20 ) • Data = Yohkoh/SXT + TRACE/EUV + BBSO/Magnetogram 19:46

  9. X-ray & EUV Foot point Brightening Sigmoid and eruption Yohkoh Soft X-ray T ≈ 1.8 ± 0.5 MK TRACE 1600 Å

  10. TRACE/1600 Å – time series 19:39:29 UT 19:40:04 19:43:28 19:45:48 19:46:24 19:46:59 19:48:11

  11. Magnetogram (BBSO) 19:46 ~ 20:05

  12. Illustration of loop structure Ⅰ. Tether cutting & sheared loop - - - D B' D D B' A A B B C A C C + + + (c) (b) Preflare (a) Moore & Sterling Apj 552, 833, 2001

  13. - - D D B B C C A A + + D B A C D A Ⅱ.. Kinked loop (c) (b) (a) • Tether cutting •  Twisted loop • Kinked loop ?  Release energy D C B A (e) A, D bightenning (d) Preflare Torok et al. AA 413, L27, 2004

  14. Future work • We will examine more examples of preflare activity from SXT/Yohkoh. : Statistical study • Case study will be carried out by making datasets which include another filtering data • Investigate the relationship between preflare activity and solar eruption

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