空间物理专业学术报告

I will first introduce the scientific capability of the 1.6m New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO). I then present some exciting new results of NST, in the areas of high resolution observations of solar flares, twisted magnetic field structures, small scale energy releases and jets, and fine structure of sunspots. In particular, I will report: 1) the sudden flare-induced rotation of asunspot. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to ~50° /hour) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. 2) We found the clear evidence that electron streaming down during a flare can induce extra transient transverse magnetic field that cause apparent rotation only at the propagating ribbon front. These kind of fronts are very narrow, in the order of 200km. Sometimes they are associated with so called negative flares in HeI 10830 and D3 lines. 3) We found evidence that episodes of precursor brightenings are initiated at a small-scale magnetic channel (a form of opposite polarity fluxes) with multiple polarity inversions and enhanced magnetic fluxes and currents, lying near the footpoints of sheared magnetic loops. The low-atmospheric origin of these precursor emissions is corroborated by microwave spectra. These high-resolution results provide evidence of low-atmospheric small-scale energy release and possible relationship to the onset of the main flare.