The Correlation Between Speed of Flare Ribbon and the Normal Component of Magnetic Field

In a simplified two-ribbon flare model, the expansion speed of flare ribbons V$_{\mathrm{r}}$ and the normal component of magnetic field B$_{\mathrm{n}}$ swept by the flare ribbons are two contributing factors in deriving the local magnetic reconnection rate, i.e., E$_{\mathrm{rec}} \quad =$ V$_{\mathrm{r}}$B$_{\mathrm{n}}$. In this project, I investigate the correlation between V$_{\mathrm{r}}$ and B$_{\mathrm{n}}$ in a case study of a two-ribbon M6.5 flare (SOL2015-06-22T18:23). The morphology and evolution of one ribbon of this flare were well captured by exceptionally high resolution H-alpha images from the Visible Imaging Spectrometer (VIS) at the 1.6 m New Solar Telescope (NST), with which I am able to track the ribbon motion and calculate V$_{\mathrm{r}}$. The photospheric line-of-sight (LOS) magnetograms, obtained with the Goode Solar Telescope(GST), are used as an approximation of B$_{\mathrm{n}}$. Based on a sample of four sections of the ribbon, a moderate negative correlation is found between V$_{\mathrm{r}}$ and B$_{\mathrm{n}}$This result suggests a tendency for flare ribbons to slow down in strong magnetic field regions.