Prominence formation by levitation-condensation at extreme resolutions

Abstract

Context. Prominences in the solar atmosphere represent an intriguing and delicate balance of forces and thermodynamics in an evolving magnetic topology. How this relatively cool material comes to reside at coronal heights, and what drives its evolution prior to, during, and after its appearance, remains an area full of open questions. Aims. We here set forth to identify the physical processes driving the formation and evolution of prominence condensations within 2.5D magnetic flux ropes. We deliberately focus on the levitation-condensation scenario, where a coronal flux rope forms and eventually demonstrates in situ condensations, revisiting it at extreme resolutions down to order 6 km in scale. Methods. We perform grid-adaptive numerical simulations in a 2.5D translationally invariant setup, where we can study the distribution of all metrics involved in advanced magnetohydrodynamic stability theory for nested flux rope equilibria. We quantify in particular convective continuum instability (CCI), thermal instability (TI), baroclinicity, and mass-slipping metrics within a series of numerical simulations of prominences formed via levitation-condensation. Results. Overall, we find that the formation and evolution of prominence condensations happens in a clearly defined sequence regardless of resolution, with background field strength between 3 and 10 Gauss. The CCI governs the slow evolution of plasma prior to the formation of distinct condensations found to be driven by the TI. Evolution of the condensations towards the topological dips of the magnetic flux rope is a consequence of these condensations initially forming out of pressure balance with their surroundings. From the baroclinicity distributions, smaller-scale rotational motions are inferred within forming and evolving condensations. Upon the complete condensation of a prominence ‘monolith’, the slow descent of this plasma towards lower heights appears consistent with the mass-slippage mechanism driven by episodes of both local current diffusion and magnetic reconnection.

Confined and eruptive catastrophes of solar magnetic flux ropes caused by mass loading and unloading

“…In fact, as concluded by Low (1996), the total mass of a flux rope should play an important role in stabilizing the rope, which is further confirmed by some recent studies (Hillier & van Ballegooijen 2013;Jenkins et al 2019;Tsap et al 2019;Fan 2020). Moreover, the total mass of a flux rope is usually not conserved but highly dynamic Gibson 2018): it either accumulates via, e.g., coronal condensation (Liu et al 2012;Xia & Keppens 2016;Jenkins & Keppens 2021), or decreases as a result of, e.g., mass unloading (Low 1996) and mass drainage processes (Bi et al 2014;Jenkins et al 2019). Therefore, to understand the influence of the varying mass on the catastrophic behaviors of coronal flux ropes is not only important to improve flux rope catastrophe theory, but also shed light on the physical scenario of different kinds of flux rope activities.…”

Plasmoid-fed prominence formation (PF$^2$) during flux rope eruption

“…The formation mechanisms of prominences are still puzzling. There are various models accounting for prominence formation as reviewed by Mackay et al (2010), and the models include levitation of chromospheric plasma (Zhao et al 2017(Zhao et al , 2019Zhao & Keppens 2020), evaporation-condensation Xia et al 2011Xia et al , 2014Xia & Keppens 2016), injection (An et al 1988;Wang 1999;Guo et al 2019), or more mixed models such as levitationcondensation of purely coronal plasma (Jenkins & Keppens 2021), as well as the three-dimensional prominence formation model by reconnection-condensation as pro-posed by Kaneko & Yokoyama (2017) and the prominence eruption model by Fan (2018).…”

A revised cone model and its application to non-radial prominence eruptions

“…Solar prominences are cool and dense plasma suspended in the hot corona (Mackay et al 2010;Parenti 2014). They usually form through direct injection (Chae et al 2000), evaporationcondensation (Karpen et al 2005, Huang et al 2021, or levitation-condensation (Jenkins & Keppens 2021) processes along the magnetic polarity inversion lines (van Ballegooijen & Martens 1989). The lifetimes of prominences range from a few weeks to a few months.…”