[P-EM11] Frontiers in solar physics

[PEM11-03] Measurements of electric fields using DKIST

*ANAN TETSU¹, Roberto Casini², Han Uitenbroek¹, Héctor Socas-Navarro³, Tom Schad¹, Jeffrey Reep⁶, Sanjiv Tiwari⁵, Lucas Tarr¹, Jiong Qiu⁹, Kiyoshi Ichimoto⁴, Sarah Jaeggli¹, Yukio Katsukawa⁷, Ayumi Asai⁸, Kevin Reardon¹, Alexandra Tritschler¹, Friedrich Wöger¹, Thomas Rimmele¹ (1.National Solar Observatory, 2.High Altitude Observatory, 3.Institute de Astrofísica de Canarias, 4.Ritsumeikan University, 5.Lockheed Martin Solar and Astrophysics Laboratory, 6.University of Hawai`i at Mānoa, 7.National Astronomical Observatory of Japan, 8.Kyoto University, 9.Montana State University)

Keywords:Solar physics, Electric field, Chromosphere, spectro-polarimetry, DKIST

Electric fields experienced by atoms play a central role in magnetic diffusion, magnetic energy dissipation, and moreover particle accelerations. Despite their importance, attempts at measuring electric fields in the solar atmosphere are scarce, because it is commonly assumed that electric fields must vanish quickly or only exist at unresolvable spatial scales due to the high electric conductivity. Using the newly commissioned US National Science Foundation's Daniel K. Inouye Solar Telescope (DKIST), we observed NOAA active region 12995 on February 23rd, 2022, in three spectral ranges, i.e., 397 nm, 630 nm, and 854 nm, using the Visible SpectroPolarimeter (ViSP). We successfully obtained Stokes spectra of Ellerman bombs, transient brightenings in the lower chromosphere associated with magnetic reconnection. At the Ellerman bomb, we discovered a broadband circular polarization in a Balmer line of the neutral hydrogen at 397 nm, H epsilon, that is consistent with the presence of an electric field. This discovery provides critical observational evidence of magnetic diffusivity enabling reconnection. In this presentation, we will discuss science objectives that this cutting-edge diagnosis enables us to address.