HAO Colloquium - Haimin Wang, NJIT/Big Bear Solar Observatory

Discovery Sciences Using 1.6m Goode Solar Telescope at Big Bear Solar Observatory
I will first introduce key instrumentation capabilities of the 1.6m Goode Solar Telescope (GST) at Big Bear Solar Observatory (BBSO). These include new development of chromospheric imaging spectroscopy and polarimetry. I will explain that some scientific capabilities of GST will continue after the 4 meter Daniel K. Inouye Solar Telescope (DKIST) is on line early 2020. GST and DKIST will be complementary. I will then introduce some discovery research results of GST, several of them were published in Nature journals:  E.g.  (1) 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. They are named as magnetic channels.  The low-atmospheric origin of these precursor emissions is corroborated by microwave spectra of newly developed radio array of NJIT . These high-resolution results provide evidence of low-atmospheric small-scale energy release and possible relationship to the onset of the main flare.  (2) With highest resolution observations, the photospheric magnetic structure changes can be tracked from flaring polarity inversion lines (PIL) propagating outwards.  These include the sudden flare-induced rotation of sunspots and increase of transverse magnetic fields near PIL. This provides some clear clue to so called “Dog vs. Tail” problem.  (3) 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.  (4) We recently found extremely strong (>5500G) fields in PIL of flaring sunspot in famous active region of September 2017, indicating formation of them below surface.  (5) We found several very interesting features in sunspot light bridges with high resolution indicating signature of magneto-convection and magnetic reconnection in small scale.


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Wednesday, August 1, 2018 - 2:00pm to 3:00pm

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