Real-time notes from Locarno WG 4, Thursday June 9 2005 Joint session with WG 2 on coronal sources Fletcher (forgot to take notes!) Bone (forgot to take notes!) Krucker (forgot to take notes until end!) Four events studied by Paula Balciunate, emphasizing 18-nov-03 Great movie comparing SXI outward-moving blob with CME Pick, Christe, Hudson, Fletcher, discussion of adiabatic suggestion recalling early work of Crannell and Matzler Ji comment on HXR/H-alpha multithermal sources (Schmahl) 9-sep-02 event; delay of 10 sec Veronig (OK, now in full note-taking mode) X-class flare with loop-top source decreasing in altitude, following Sui & Holman 3-Nov-03 event (same AR as for White presentation, born on disk) Nice movie combining 12-15 and 70-100 keV images H-alpha loop tops seen in emission against the disk; PFL above limb SXI movie sort of nondescript height-vs-time combining H-alpha, EIT, SXI, RHESSI, hot above cool as in April 21 2002 over 10 hours Footpoint colorcoded on MDI; looptop shows downward swing prior to upward motion Early phase also shows hot above, cool below? Increasing 20/15 keV ratio SXI also sees downward motion. Velocities are maybe 45 km/s Spectra show looptops with isothermal superhot shape Late phase consistent with standard 2D model, but 50% height decrease in early phase looks different Superhot before particle acceleration Discussion of projection effect but note spectral changes suggesting different physics Early phase 10^10 already -> 10^12 later on to drive H-alpha to emission Reconnection-induced shrinkage (Svestka); current sheet (Sui et al); collapsing trap (Somov-Kosugi, Karlicky) Cartoons of collapsing trap, betatron heating and acceleration Height-vs-time plots of thermal BS in collapsing trap predict hot-above Discussion (Gallagher, Hudson, Fletcher, Dennis) - why does the same cartoon "predict" downward motions sometimes, and upward motions (eg Shibata) at other times? Some handwaving required (Henoux)? Ji comment - what footpoint motions are predicted? Heated discussion on what CSHKP predicts here... (Hudson, Fletcher, et al) White comment on prior structure in corona (concern too about Sui-Holman; Krucker comment about 23-Jul early phase) Dauphin Same flare, Nancay/SXI data, effect of CME on radio emissions Striking broad-band source ffrom 09:57, with modulations, following type II and IV sources Nancay images show change of morphology at this epoch SXI sees CME-associated rising loops from 09:50, difference images LASCO hvt seems to match the SXI front position fairly well; can combine the hvt plots with a quadratic fit 432 MHz sources are behind the front at 09:57:33 and are modulated; suggest tearing-mode instability Consistent with Gallagher et al.; suggest two phases of CME acceleration corresponding to two hard X-ray phases Clear imaging of type II outside the SXI loop expansion and in height sequence Radio spectra distinguish plasma component and gyrosynchrotron component; from theory get 1 G field; if no Razin then n<3e7 Find Dulk-Marsh consistency with RHESSI spectrum @ -1.6 (MeV range) Conclusion: gyro at metric following CME; type II decimetric ahead of CME; metric below CME and possibility of instability-driven modulations White Movie of earlier Nov. 3 flare from Nobeyama and RHESSI: loop, no footpoint in HXR; jet at 35 GHz; preflare radio structure with complicated morphology After Coffee Break Session Topic : Footpoints Hudson : White Light Flares: Trace and RHESSI Observations Original (white) light flare, Carrington 1859, first flare terrestrial response, three axis compas readings is noted to this flare, evidence of a shock wave a few days later possibly from CME from that flare, top 5% of CMEs speed, 2000 km/s white light usually formed deep in the photosphere, associates very well with x-rays 10 MeV protons can get down to 10^24 cm^2 so down to photosphere contribution functions needs to be used to calculate where th emission is coming from fluctuations of white light are too fast to be caused by the protons 11 well covered events X:0 M7 C3 all had white light so no tresholding effect...? excess of ultraviolet associated with solar activity, this emission may be detected by TRACE 24 jul 04 C1.6 world record small white light flare good coincidence between ultraviolet and white light contours for that event M4.9 july 26 02, white light time curve is impulsive, neupert like white light kernel emission from a loop top, 12 nov 02, gradual emission with impusilve emission from white light footpoints conclusions, trace show rapid small scale features resembling UV sources are small patches every flare is a white light flare, emission correlated to total energy contrasts can exceed 100% compared to background photosphere seeing bright low-temperature emission like 10000 C just like stellar flares not just UV extension (white light is created by recombination) uv/wl footpoints are tiny, a few arcseconds Henoux : Information on particle acceleration and transport derived from solar solar flare spectropolarimetry anysotropy leads to polarization in halpha polarization fraction is related to electron energy as measured in the laboratory polarization switches above a certain energy, E0 = 200 keV. polarization is dependent on direction and therefore along the B field, need to assume whether they are circling the B field or not 15-jun-01 event deriving the stokes parameters is tricky images are create by scanning a slit across the sun polarization island is found to be on the border of the flare, ~4% polarization is always a little higher in hbeta one minute of time to scan over 100 arcseconds peaks in radial polarization could be from low enery protons moving along B or electrons circling around B or return current electrons moving along B norma and smith used to estimate return current spectrum return current energy can be either above or below E0 depending on ambient density. interpretation : tangential polarization is associated with upflow related to reconnection. Fletcher : 17 Jul 2002 tracking individual flare kernels in TRACE UV, 4 ribbon flare complex ribbons developped an algorithm to track each little kernel interactions between two different active regions calculated the rate of change of magnetic flux, reconnection rate good correlation in time between reconnection rate and intensity variations 25% of peaks are correlated which is significant compared to monte carlo simulation RHESSI contours lie along ribbons and seem to be where reconnection rate is highest finding correlations in peaks in time is difficult, used wavelet a trous can seperate out bursts from overall evolution find good correlation between some kernels some are found with delays, 5 sec delays