The Merging of a Coronal Dimming and the Southern Polar Coronal Hole

Abstract

We report on the merging between the southern polar coronal hole and an adjacent coronal dimming induced by a coronal mass ejection on 2022 March 18, resulting in the merged region persisting for at least 72 hrs. We use remote sensing data from multiple co-observing spacecraft to understand the physical processes during this merging event. The evolution of the merger is examined using Extreme-UltraViolet (EUV) images obtained from the Atmospheric Imaging Assembly onboard the Solar Dynamic Observatory and Extreme Ultraviolet Imager onboard the Solar Orbiter spacecraft. The plasma dynamics are quantified using spectroscopic data obtained from the EUV Imaging Spectrometer onboard Hinode. The photospheric magnetograms from the Helioseismic and Magnetic Imager are used to derive magnetic field properties. To our knowledge, this work is the first spectroscopical analysis of the merging of two open-field structures. We find that the coronal hole and the coronal dimming become indistinguishable after the merging. The upflow speeds inside the coronal dimming become more similar to that of a coronal hole, with a mixture of plasma upflows and downflows observable after the merging. The brightening of bright points and the appearance of coronal jets inside the merged region further imply ongoing reconnection processes. We propose that component reconnection between the coronal hole and coronal dimming fields plays an important role during this merging event, as the footpoint switching resulting from the reconnection allows the coronal dimming to intrude onto the boundary of the southern polar coronal hole.

17 pages, 8 figures, accepted for publication in The Astrophysical Journal

References in corpus (18)

• The Solar Orbiter mission -- Science overview
• Multi-scale Gaussian normalization for solar image processing
• Origins of the Ambient Solar Wind: Implications for Space Weather
• Magnetic Reconnection as the Driver of the Solar Wind
• Transient small-scale brightenings in the quiet solar corona: a model for campfires observed with Solar Orbiter
• Verification of high-speed solar wind stream forecasts using operational solar wind models
• Coronal Holes and Open Magnetic Flux over Cycles 23 and 24
• The Eruption from a Sigmoidal Solar Active Region on 2005 May 13
• Multiwavelength Study of Equatorial Coronal-Hole Jets
• Characteristics of Low-Latitude Coronal Holes near the Maximum of Solar cycle 24
• Upflows in the upper solar atmosphere
• Spectroscopy and Differential Emission Measure diagnostics of a coronal dimming associated with a fast halo CME
• Dark jets in solar coronal holes
• Imaging evidence for solar wind outflows originating from a CME footpoint
• Multi-stage reconnection powering a solar coronal jet
• Determining the source and eruption dynamics of a stealth CME using NLFFF modelling and MHD simulations
• Widespread Occurrence of High-Velocity Upflows in Solar Active Regions
• Plasma Upflows Induced by Magnetic Reconnection Above an Eruptive Flux Rope

Cited by in corpus (3)

• First Perihelion of EUI on the Solar Orbiter mission
• Slow Solar Wind Connection Science during Solar Orbiter's First Close Perihelion Passage
• Synthetic Remote-sensing and In-situ Observations of Fine-scale Structure in a Pseudostreamer Coronal Mass Ejection through the Solar Corona