Very high-resolution observations of the solar atmosphere in H I Lyman alpha and Fe IX-X at 17.4 nm as seen by EUI aboard Solar Orbiter

The Extreme Ultraviolet Imager (EUI) aboard Solar Orbiter consists of three telescopes, the Full Sun Imager (FSI) and two High Resolution Imagers (HRIs). The two HRI telescopes provide images of the base of the corona, near to the chromosphere, and of the 1 million K corona. In fact, the HRI-EUV telescope operates around 17.4 nm to obtain images dominated by emission from lines generated from Fe-IX and X ions, formed at about 1 MK, while the HRI-LYA telescope provides narrow band images dominated by the H I Lyman alpha line at 121.6 nm, formed in the upper chromosphere/lower transition region of the solar atmosphere around 20,000 K. Thus, the two imagers provide a powerful diagnostics of the solar structural organization, in terms of loop hierarchies and connectivity. Here we present an analysis of the first two near-simultaneous (within 15s) high-resolution images of the solar quiet atmosphere obtained near disk center by the two high-resolution telescopes on May 30th 2020, during the commissioning phase of the mission , when Solar Orbiter was at about 0.56 AU from the Sun.