SIMULTANEOUS OBSERVATION OF RECONNECTION INFLOW AND OUTFLOW ASSOCIATED WITH THE 2010 AUGUST 18 SOLAR FLARE

We report the simultaneous extreme-ultraviolet observation of magnetic reconnection inflow and outflow in a flare on 2010 August 18 observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We found that during the rise phase of the flare, some plasma blobs appeared in the sheet structure above the hot loops. The plasma blobs were ejected bidirectionally along the sheet structure (outflow), at the same time as the threads visible in extreme-ultraviolet images moved toward the sheet structure (inflow). The upward and downward ejection velocities are 220-460 km s{sup -1} and 250-280 km s{sup -1}, respectively. The inflow speed changed from 90 km s{sup -1} to 12 km s{sup -1} in 5 minutes. By using these velocities, we estimated the nondimensional reconnection rate, which we found to vary during this period from 0.20 to 0.055. We also found that the plasma blobs in the sheet structure collided or merged with each other before they were ejected from the sheet structure. We hypothesize that the sheet structure is the current sheet and that these plasma blobs are plasmoids or magnetic islands, which could be important for understanding the dynamics of the reconnection region.

[1]  P. Chen,et al.  A Reexamination of the Evidence for Reconnection Inflow , 2004 .

[2]  M. Shimojo,et al.  Downflow Motions Associated with Impulsive Nonthermal Emissions Observed in the 2002 July 23 Solar Flare , 2004 .

[3]  L. Golub,et al.  ATMOSPHERIC IMAGING ASSEMBLY OBSERVATIONS OF HOT FLARE PLASMA , 2011 .

[4]  Jun Zhang,et al.  OBSERVATIONS OF THE MAGNETIC RECONNECTION SIGNATURE OF AN M2 FLARE ON 2000 MARCH 23 , 2009, 0907.4541.

[5]  Eric Ronald Priest,et al.  Magnetic Reconnection: MHD Theory and Applications , 2000 .

[6]  K. Shibata,et al.  X-Ray Plasma Ejection Associated with an Impulsive Flare on 1992 October 5: Physical Conditions of X-Ray Plasma Ejection , 1998 .

[7]  Harold P. Furth,et al.  Finite‐Resistivity Instabilities of a Sheet Pinch , 1963 .

[8]  T. Hirayama.  Theoretical model of flares and prominences , 1974 .

[9]  Saku Tsuneta,et al.  Moving Plasmoid and Formation of the Neutral Sheet in a Solar Flare , 1997 .

[10]  Eugene N. Parker,et al.  Sweet's mechanism for merging magnetic fields in conducting fluids , 1957 .

[11]  Chang Liu,et al.  A RECONNECTING CURRENT SHEET IMAGED IN A SOLAR FLARE , 2010, 1009.4912.

[12]  T. Kosugi,et al.  A loop-top hard X-ray source in a compact solar flare as evidence for magnetic reconnection , 1994, Nature.

[13]  M. Shimojo,et al.  Reconnection Rate in the Decay Phase of a Long Duration Event Flare on 1997 May 12 , 2002 .

[14]  K. Shibata,et al.  Plasmoid-induced-reconnection and fractal reconnection , 2001, astro-ph/0101008.

[15]  M. Karlický,et al.  Drifting pulsating structures generated during tearing and coalescence processes in a flare current sheet , 2007 .

[16]  R. S. Steinolfson,et al.  The growth of the tearing mode: Boundary and scaling effects , 1983 .

[17]  M. Shimojo,et al.  Hot-Plasma Ejections Associated with Compact-Loop Solar Flares , 1995 .

[18]  K. Shibata.  Evidence of Magnetic Reconnection in Solar Flares and a Unified Model of Flares , 1998 .

[19]  J. Qiu,et al.  Direct Observation of High-Speed Plasma Outflows Produced by Magnetic Reconnection in Solar Impulsive Events , 2007, 0709.2329.

[20]  The Graduate University for Advanced Studies,et al.  MULTIPLE PLASMOID EJECTIONS AND ASSOCIATED HARD X-RAY BURSTS IN THE 2000 NOVEMBER 24 FLARE , 2010, 1301.6241.

[21]  A. A. Schekochihin,et al.  Instability of current sheets and formation of plasmoid chains , 2007 .

[22]  G. Holman,et al.  Evidence for the Formation of a Large-Scale Current Sheet in a Solar Flare , 2003 .

[23]  D. McKenzie,et al.  SUMER spectral observations of post-flare supra-arcade inflows , 2003 .

[24]  Takaaki Yokoyama,et al.  What is the condition for fast magnetic reconnection , 1994 .

[25]  A. Foster,et al.  Fe IX CALCULATIONS FOR THE SOLAR DYNAMICS OBSERVATORY , 2011, 1107.0470.

[26]  C. J. Wolfson,et al.  Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) , 2008 .

[27]  E. Christian,et al.  The STEREO Mission: An Introduction , 2008 .

[28]  H. Hudson,et al.  X-Ray Observations of Motions and Structure above a Solar Flare Arcade , 1999 .

[29]  H. Hara,et al.  A Spectroscopic Observation of a Magnetic Reconnection Site in a Small Flaring Event , 2006 .

[30]  A. Emslie,et al.  The Physics of Solar Flares , 2009 .

[31]  J. Raymond,et al.  Direct Observations of the Magnetic Reconnection Site of an Eruption on 2003 November 18 , 2005 .

[32]  Takaaki Yokoyama,et al.  Clear Evidence of Reconnection Inflow of a Solar Flare , 2001 .

[33]  Chengcai Shen,et al.  NUMERICAL EXPERIMENTS ON FINE STRUCTURE WITHIN RECONNECTING CURRENT SHEETS IN SOLAR FLARES , 2011 .

[34]  Measurement of the Energy Release Rate and the Reconnection Rate in Solar Flares , 2005, astro-ph/0507327.

[35]  M. Ugai,et al.  Magnetic field-line reconnexion by localized enhancement of resistivity: Part 1. Evolution in a compressible MHD fluid , 1977, Journal of Plasma Physics.

[36]  T. Tajima,et al.  Current loop coalescence model of solar flares , 1987 .

[37]  R. Kopp,et al.  Magnetic reconnection in the corona and the loop prominence phenomenon , 1976 .

[38]  R. Treumann.  Origin of resistivity in reconnection , 2001 .

[39]  Jean-Pierre Wuelser,et al.  EUVI: the STEREO-SECCHI extreme ultraviolet imager , 2004, SPIE Optics + Photonics.

[40]  N. W. Cant,et al.  Lewis and Bronsted Acid Sites on Silica-Alumina , 1966, Nature.

[41]  K. Shibata,et al.  Statistical Analysis of Reconnection Inflows in Solar Flares Observed with SOHO EIT , 2006 .

[42]  D. McKenzie,et al.  QUANTITATIVE EXAMINATION OF A LARGE SAMPLE OF SUPRA-ARCADE DOWNFLOWS IN ERUPTIVE SOLAR FLARES , 2011, 1101.1540.

[43]  Durgesh Tripathi,et al.  SDO/AIA response to coronal hole, quiet Sun, active region, and flare plasma , 2010 .