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Study of preflare activity in Yohkoh SXT images

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kalea
14 diapositives · 260 Views · Aug 24, 2014

This study explores the independent energy release and initial flare activity observed in solar phenomena using Yohkoh SXT data. We conduct a statistical analysis of preflare events, investigating the relationship between soft X-ray precursors and subsequent flares. Our research encompasses both statistical evaluations and specific case studies, where we compare preflare events with other data, including EUV and magnetograms. The findings aim to enhance our understanding of the physical mechanisms connecting preflare activity to major solar eruptions.

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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