On the short term stability and tilting motion of a well-observed low-latitude solar coronal hole
arXiv:2309.11100 · doi:10.1051/0004-6361/202347180
Abstract
The understanding of the solar magnetic coronal structure is tightly linked to the shape of open field regions, specifically coronal holes. A dynamically evolving coronal hole coincides with the local restructuring of open to closed magnetic field, which leads to changes in the interplanetary solar wind structure. By investigating the dynamic evolution of a fast-tilting coronal hole, we strive to uncover clues about what processes may drive its morphological changes, which are clearly visible in EUV filtergrams. Using combined 193A and 195A EUV observations by AIA/SDO and EUVI/STEREO_A, in conjunction with line-of-sight magnetograms taken by HMI/SDO, we track and analyze a coronal hole over 12 days to derive changes in morphology, area and magnetic field. We complement this analysis by potential field source surface modeling to compute the open field structure of the coronal hole. We find that the coronal hole exhibits an apparent tilting motion over time that cannot solely be explained by solar differential rotation. It tilts at a mean rate of ~3.2°/day that accelerates up to ~5.4°/day. At the beginning of May, the area of the coronal hole decreases by more than a factor of three over four days (from ~13 * 10^9 km^2 to ~4 * 10^9 km^2), but its open flux remains constant (~2 * 10^20 Mx). Further, the observed evolution is not reproduced by modeling that assumes the coronal magnetic field to be potential. In this study, we present a solar coronal hole that tilts at a rate that has yet to be reported in literature. The rate exceeds the effect of the coronal hole being advected by either photospheric or coronal differential rotation. Based on the analysis we find it likely that this is due to morphological changes in the coronal hole boundary caused by ongoing interchange reconnection and the interaction with a newly emerging ephemeral region in its vicinity.
Accepted in A&A September 15, 2023; 10 pages, 8 figures
References in corpus (16)
- Small-scale filament eruptions as the driver of solar coronal hole X-ray jets
- Interchange reconnection as the source of the fast solar wind within coronal holes
- Coupling from the photosphere to the chromosphere and the corona
- Similarities and Differences between Coronal Holes and the Quiet Sun: Are Loop Statistics the Key?
- Characteristics of Low-Latitude Coronal Holes near the Maximum of Solar cycle 24
- Differential Emission Measure Plasma Diagnostics of a Long-Lived Coronal Hole
- Segmentation of Coronal Holes Using Active Contours Without Edges
- Statistical properties of coronal hole rotation rates: Are they linked to the solar interior?
- Variations in Finite Difference Potential Fields
- How the area of solar coronal holes affects the properties of high-speed solar wind streams near Earth -- An analytical model
- Statistical Approach on Differential EmissionMeasure of Coronal Holes using the CATCH Catalog
- Properties of stream interaction regions at Earth and Mars during the declining phase of SC 24
- On the Dependency between the Peak Velocity of High-speed Solar Wind Streams near Earth and the Area of Their Solar Source Coronal Holes
- Influence of coronal hole morphology on the solar wind speed at Earth
- Synchronization of Small-scale Magnetic Features, Blinkers, and Coronal Bright Points
- Differences in physical properties of coronal bright points and their ALMA counterparts within and outside coronal holes