Diversity of morphology of type II spicules in MURaM-ChE simulations
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2026
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| _version_ | 1866917531700166656 |
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| author | Chandra, Sanghita Cameron, Robert Przybylski, Damien Solanki, Sami K. |
| author_facet | Chandra, Sanghita Cameron, Robert Przybylski, Damien Solanki, Sami K. |
| contents | Spicules are ubiquitous, small-scale features in the solar atmosphere, exhibiting a jet-like appearance most clearly identified by their apparent motion in off-limb observations. While they are often interpreted as narrow, thread-like structures, their true three-dimensional (3D) structure remains unknown. We aim to uncover the 3D morphology and dynamics of fast-evolving spicules (type II) using a MURaM-ChE simulation. We use a H$α$ proxy that has been developed using non-equilibrium (NE) hydrogen populations in MURaM-ChE. The proxy, modelled as an escape probability, is synthesised to isolate on-disc as well as off-limb H$α$ wing features. The 3D structure of these features is investigated using the 3D information on opacity in H$α$. We identify type II spicules, with unique 3D morphologies: the dominant being thread-like and slab-like. The appearance of spicules as slabs or threads is a function of time and Doppler velocity. The spicules extending above the spicule-forest (2Mm -3Mm above the surface) tend to be located at quasi-separatrix layers (QSLs). We find that the spatially resolved contributions to the opacity of spicules are often similar for spicules synthesised in the horizontal direction, and their on-disk rapid blueshifted excursion (RBE) synthesised in the vertical direction at the same Doppler velocity of 37km/s. This confirms that RBEs are indeed the on-disc counterparts of spicules. Furthermore, our analysis indicates that cross-field motions can significantly contribute to spicule dynamics. Spicules exhibit a range of morphologies, including both slab-like and thread-like structures. Their observed appearance depends strongly on line-of-sight projection and Doppler sampling. Spicules are preferentially located at QSLs, highlighting the role of magnetic topology in driving spicular dynamics. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2605_25886 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Diversity of morphology of type II spicules in MURaM-ChE simulations Chandra, Sanghita Cameron, Robert Przybylski, Damien Solanki, Sami K. Solar and Stellar Astrophysics Spicules are ubiquitous, small-scale features in the solar atmosphere, exhibiting a jet-like appearance most clearly identified by their apparent motion in off-limb observations. While they are often interpreted as narrow, thread-like structures, their true three-dimensional (3D) structure remains unknown. We aim to uncover the 3D morphology and dynamics of fast-evolving spicules (type II) using a MURaM-ChE simulation. We use a H$α$ proxy that has been developed using non-equilibrium (NE) hydrogen populations in MURaM-ChE. The proxy, modelled as an escape probability, is synthesised to isolate on-disc as well as off-limb H$α$ wing features. The 3D structure of these features is investigated using the 3D information on opacity in H$α$. We identify type II spicules, with unique 3D morphologies: the dominant being thread-like and slab-like. The appearance of spicules as slabs or threads is a function of time and Doppler velocity. The spicules extending above the spicule-forest (2Mm -3Mm above the surface) tend to be located at quasi-separatrix layers (QSLs). We find that the spatially resolved contributions to the opacity of spicules are often similar for spicules synthesised in the horizontal direction, and their on-disk rapid blueshifted excursion (RBE) synthesised in the vertical direction at the same Doppler velocity of 37km/s. This confirms that RBEs are indeed the on-disc counterparts of spicules. Furthermore, our analysis indicates that cross-field motions can significantly contribute to spicule dynamics. Spicules exhibit a range of morphologies, including both slab-like and thread-like structures. Their observed appearance depends strongly on line-of-sight projection and Doppler sampling. Spicules are preferentially located at QSLs, highlighting the role of magnetic topology in driving spicular dynamics. |
| title | Diversity of morphology of type II spicules in MURaM-ChE simulations |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2605.25886 |