Swirling motions, fast plasma flows and small-scale chromospheric eruptions in a sunspot light-bridge

Thursday, 18 December 2014
Santiago Vargas Domínguez, Big Bear Solar Observatory, Big Bear City, CA, United States; Universidad Nacional de Colombia, Observatorio Astronomico Nacional, Bogota, Colombia and Alexander G Kosovichev, New Jersey Institute of Technology, Edison, NJ, United States
Multi-wavelength observations with the 1.6m New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO) have evidenced a complex dynamics of sunspots. We present photospheric and chromospheric observations of a sunspot light-bridge in AR 11850 taken on 29 September 2013. The NST/BFI data in the TiO reveal strong shearing and high-speed swirling flows in the light-bridge. Scanning of the H-alpha spectral line shows strong chromospheric downflows in the red wing near the outermost part of the light-bridge. Chromospheric structuring around the spot appears to be more complex due to the presence of the light-bridge. We detect small-scale explosive events that are likely to be boosted by the interactions of magnetic field lines at the chromospheric level and therefore triggered by the evolution of the light bridge in the photosphere beneath. In particular a very localized explosive event reaching the transition region and coronal temperatures is observed from simultaneous IRIS and SDO data.