Probing Small-scale Magnetic Reconnection with DKIST

Authors: Joao M. da Silva Santos (NSO), Eric Dunnington (RPI), Robert Jarolim (HAO), Sanja Danilovic (SU/ISP), Serena Criscuoli (NSO)

Magnetic reconnection at small spatial scales is a key driver of energy release and plasma dynamics in the solar atmosphere. We present high-resolution DKIST observations of a compact brightening in an active region, captured with the Visible Broadband Imager (VBI) and Visible Spectro-Polarimeter (ViSP). This unusual event exhibits both classical Ellerman bomb-like morphology in Hβ and more complex Ca II K emission patterns characteristic of microflares or UV-bursts. No significant coronal is detected. Using multi-line, non-LTE inversions, we infer the stratification of atmospheric parameters, revealing localized enhancements in temperature, velocity, and microturbulence in the upper photosphere and low chromosphere. Nonlinear force-free extrapolations of the ViSP vector magnetogram show a compact fan-spine topology with enhanced squashing factors in a dome structure surrounding the minority polarity. Our findings provide evidence of low-altitude (<1 Mm) reconnection along quasi-separatrix layers, possibly triggered by continuous convergence of magnetic elements, giving rise high-velocity (alfvenic) flows in the photosphere and chromosphere.