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Physics of Chromospheric Evaporation in Solar Flares

２００３ . Apr 　２８　　　 Solar Seminar. Physics of Chromospheric Evaporation in Solar Flares. K. Shibata. Best 10 of Most cited papers based on Hida-DST observations 6 th -10 th (ADS ： 2003 Apr 27). 6. Brueckner, G. E., et al. (1988) ApJ, 335, 986 ------------------- 18 回

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Physics of Chromospheric Evaporation in Solar Flares

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  1. ２００３.Apr　２８　　　Solar Seminar Physics of Chromospheric Evaporation in Solar Flares K. Shibata

  2. Best 10 of Most cited papers based on Hida-DST observations 6th-10th(ADS：2003 Apr 27) • 6. Brueckner, G. E., et al. (1988) ApJ, 335, 986 ------------------- 18回 • 7. Kurokawa, H., Hanaoka, H., et al. (1987) Solar Phys., 108, 251 --------- 17 • 8. Tsubaki, T., et al. (1988) PASJ, 40, 121 ----------------- 17 • 9. Culhane, J. L. et al. (1994) Solar Phys., 153, 307 -------- 16 • 10. Kitai, R. (1986) Solar Phys., 104, 287 -------- 16

  3. Best 10 of Most cited papers based on Hida-DST observations 1st – 5th • 1. • ２. Ichimoto, K. (1987) Solar Phys. 39, 329 ------------ 22 • ３．Kurokawa, H., (1987) Solar Phys., 113, 259 --------- 20 • ４. Kurokawa, H. (1989) Space Sci. Rev. 51, 49 ------- 19 • 5. Kurokawa, H., Takakura, T., et al. (1988) PASJ, 40, 357 ------------------ 18 Ichimoto, K. and Kurokawa, H. (1984) Solar Phys. 93, 105 ---------- 69回

  4. Introduction: what is flare ? • Preflare energy buid-up • Trigger • Energy release --- magnetic reconnection • Heating • Particle acceleration • Mass ejection • Shock wave • Energy transport • Nonthermal electron beam • Heat conduction • Chromospheric evaporation • Radiation

  5. Energy buidup

  6. Energy release – magnetic reconnection Unified model (Shibata 1997)

  7. Energy transport Bright soft X-ray Flare loop Is a Consequence of chromospheric evaporation !

  8. Neupert (1968) ApJ 153, 59 • obs. soft X-ray line + microwave in flares => “additional material, not originally at coronal temperature, is rapidly heated and elevated to high stages of ionization during the event”

  9. Neupert effect • Time derivative of soft X-ray intensity ~ hard X-ray intensity Soft X-ray Hard X-ray microwave Dennis and Zarro (1993) OK(80%) Lee et al. (1995) no Tomczak (1999) spatial info OK

  10. Theory and numerical simulations ofchromospheric evaporation

  11. Hirayama (1974) • “Particles observed in the corona and the solar wind are evaporated from the chromosphere during the flare”

  12. Evaporation cooling(Antiochos and Sturrock 1978) t －2/7 ∝ T =const.

  13. Nagai (1980) Solar Phys.1D-Hydro-sim. F ~ 3x10^{9} erg/cm^2/s

  14. Nagai (1980) F ~ 3x10^{9} erg/cm^2/s

  15. Nagai (1980) F ~ 3x10^{9} erg/cm^2/s

  16. Nagai (1980) F ~ 3x10^{9} erg/cm^2/s

  17. Nagai (1980) Strong downflow ~ 40km/s F ~ 3x10^{10} erg/cm^2/s

  18. Fisher et al. (1985) ApJ thick target heating by nonthermal electrons

  19. Scaling law (Fisher 1985) Flare maximum temperature Maximum velocity of evaporation upward flow

  20. MHD Simulation of Reconnection with Heat Conduction and Chromospheric Evaporation (Yokoyama and Shibata 1998, 2001)

  21. Flare temperature scaling law（Yokoyama and Shibata 1998） Reconnection heating = conduction cooling

  22. Simulation of soft X-ray and radio observations

  23. Prediction of Yokoyama-Shibata 1998

  24. Observational evidence of chromospheric evaporation

  25. Antonucci et al. (1982) SP 78, 107detected blue shift of evaporation upward flow

  26. Antonucci et al. (1982)

  27. Antonucci et al. (1982)

  28. Ichimoto and Kurokawa (1984) SP 93, 105solved red asymmetry problem • “The spectroscopy of Ichimoto and Kurokawa (1984) represents the zenith of what has been achieved up to now by conventional photographic spectroscopy” (Canfield et al. 1990)

  29. Can red asymmetry be explained by absorbing material ?

  30. Redshift cannot be explained byabsorbtion

  31. Temporal variation of downward velocity in theflare emitting region (Ichimoto and Kurokawa 1984) ●wing shift x peak shift ○Halpha intensity

  32. Ichimoto and Kurokawa (1984) • H alpha red asymmetry (40-100 km/s) is is due to downward motion of the compressed chromospheric flare region produced by the impulsive heating by energetic electrons or thermal conduction

  33. Canfield et al. (1990) H alpha + Hard X-ray confirm Ichimoto-Kurokawa, but show also blue shifted H alpha emssion

  34. Wuelser et al. (1992) ApJ 384, 341 • SMM X-ray + Sacpeak H alpha line upflowing coronal material (as seen in Ca XIX soft X-rays) and downflowing chromospheric material (as seen in redshifted H alpha) appear simultaneously at the beginning of impuslive hard X-ray emission, with the total momenta of oppositely directed plasmas being equal to the observational uncertainties

  35. Wuelser et al. (1992)

  36. Nogami, Brooks, Isobe, Shibata,,,(2003-2004) • We want to observe stellar flares with the scientific purpose similar to that of Wuelser et al. (1992)’s solar flare observations by using both Subaru and XMM-Newton

  37. Further developments • Wuelser et al. (1994) • Yohkoh-Mees • Upflowing coronal plasma and downflowing chromospheric plasma at the same locations, at footpoints of a soft X-ray loop • Footpoints are not heated by nonthermal electrons but by heat conduction • Shoji and Kurokawa (1995) • Hida DST • Impulsive phase spectra of flares for Halpha, CaIIK, HeID3, NaID1,2, other metalic lines • Emitting region of chromospheric flare consists of two regions; • Thin fast downward moving layer, and stationary optically thick layter (for metalic lines)

  38. Latest paper • Teriaca et al. (2003) ApJ 588, 596 • SOHO/CDS, SacPeak, GOES first quasi-simultaneous and spatially resolved observations of velocity fields during the impulsive phase of a flare, in both the chromosphere and upper atmospehre

  39. Shimojo et al. (2001)evaporation occurs also in X-ray jets (see also Miyagoshi and Yokoyama 2003)

  40. Shimojo-Shibata (2000) ApJ

  41. X-ray jets are evaporation flows(Shimojo and Shibata 2000)

  42. Future Subjects • Spectroscopic observatsions of flares should be done at Hida with DST as the most important priority projects in 2003 • H alpha red asymmetry of surges would be observed (at the footpoint of surges/X-ray jets) • stellar flares observations will be interesting to detect evaporation flows • Remaining puzzles: • blue shifts ? • Nonthermal electrons or thermal conduction ? • Develop further MHD simulations with evaporation in 2D and 3D, incorporating effects of nonequilibrium ionization, nonthermal electrons, and radiative transfer

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