First Solar Orbiter observation of a dark halo in the solar atmosphere
Serena Maria Lezzi, David M. Long, Vincenzo Andretta, Deborah Baker,, Antoine Dolliou, Mariarita Murabito, Susanna Parenti, Natalia Zambrana, Prado

TL;DR
This paper presents the first high-resolution observation of a dark halo around a solar active region, revealing complex fine structures and suggesting a deep connection between the halo and the lower solar atmosphere.
Contribution
It provides the first detailed analysis of a dark halo's fine structure using high-resolution EUV and Lyα observations from Solar Orbiter, linking it to photospheric magnetic features.
Findings
Dark halo exhibits interconnected bright and dark EUV structures not seen in quiet Sun.
Bright EUV bundles are present across multiple TR lines and correlate with photospheric magnetic footprints.
The dark halo likely originates from the low solar atmosphere, indicating a deep connection with the active region.
Abstract
Solar active regions (ARs) are often surrounded by dark large areas of reduced emission compared to the quiet Sun, observed at various wavelengths corresponding to chromosphere, transition region (TR) and corona, and known as Dark Halos (DHs). DHs have been insufficiently studied, and the mechanisms behind their darker emission remain unclear. This study aims to investigate for the first time the fine structure of a DH observed by the EUV High Resolution Imager (HRI) onboard the ESA's Solar Orbiter (SO) mission and its appearance in the TR. We utilized the extensive 1-hour dataset from SO on 19 March 2022, which includes high-resolution observations of NOAA 12967 and part of the surrounding DH. We analyzed the dynamics of the HRI DH fine structure and its appearance in the HRI image and the Spectral Imaging of the Coronal Environment (SPICE) Ly, C…
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Taxonomy
TopicsSolar and Space Plasma Dynamics · History and Developments in Astronomy
