Periodic Reporting for period 4 - PROMINENT (Solar prominences: unraveling the ultimate condensation catastrophe)
Okres sprawozdawczy: 2024-03-01 do 2024-08-31
PROMINENT investigated the "coolest" part of the million-degree hot solar atmosphere or corona: the condensations known as "solar prominences". These play an important role in space weather, the relentless bombardment of solar plasma onto our Earth's magnetosphere. Solar Coronal Mass Ejections (CMEs) often expel prominence matter into the heliosphere, but CME models frequently ignore the prominence plasma. In the solar corona, these spontaneous condensations are observed to occur on many length and time scales, from the smallest condensed structures detectable as "coronal rain", to enormous prominences: clouds of cool and dense material suspended in the atmosphere by the Sun's magnetic field, thereby seemingly defying gravity. Our current understanding of these coronal rain events, as well as of the large-scale prominences or filaments, is severely blurred due to present-day observational resolution limits. We use modern open-source software, developed and made available by us to the entire astrophysical community, to go beyond these observational limits. Our grid-adaptive, massively parallel software allows us to identify and predict detailed solar prominence and coronal rain aspects, that may be verifiable in future, higher resolution and higher-cadence observations. The overall objectives include the fundamental physical processes behind the condensations, by using both linear and nonlinear models of the governing conservation laws.
The PROMINENT project brought us deep insight into how prominences and coronal rain relate to radiative loss driven thermal instability. We modeled both phenomena at resolutions beyond those observationally possible, and identified various dynamical details in fully multi-dimensional, highly resolved simulations. Our open-source software (Legolas and mpi-amrvac) is used worldwide, and directly results from our ERC-funded team effort.
The PROMINENT project brought us deep insight into how prominences and coronal rain relate to radiative loss driven thermal instability. We modeled both phenomena at resolutions beyond those observationally possible, and identified various dynamical details in fully multi-dimensional, highly resolved simulations. Our open-source software (Legolas and mpi-amrvac) is used worldwide, and directly results from our ERC-funded team effort.
The PROMINENT project realized major breakthroughs. A crowning achievement appeared on the cover image of Nature Astronomy, in August 2022, see Nature Astronomy 6, 942-950. This extended our earlier 2.5-dimensional simulation in 2021, Astronomy & Astrophysics 646, A134 where we could afford unprecedented resolution: a factor 10 beyond the modern high resolution observational views. The various phases found in the evolution of the prominence can be linked to quantifications of all the linear eigenmodes of a solar flux-rope system. These include the Convective Continuum Instability (causing motions along individual flux surfaces), the thermal instability (a local runaway effect due to radiative losses), and the effect of mass slippage due to magnetic reconnections. Another breakthrough represents the open-source software MPI-AMRVAC (http://amrvac.org(odnośnik otworzy się w nowym oknie)) where we added a two-fluid plasma-neutral model (B. Popescu Braileanu & R. Keppens, 2022, A & A 664, A55) along with means to handle radiative effects beyond optically thin assumptions (N. Moens, et al., 2022, Astronomy & Astrophysics 657, A81). This software is now fully documented and described in several demonstration papers such as 2021, Computers & Mathematics With Applications 81, 316-333 or the main code paper accompanying our MPI-AMRVAC 3.0 release: Keppens et al, 2023, A&A 673, A66. The same software featured in the most self-consistent model of a solar flare: in 2020, ApJ 896, 97, where we combined a large-scale magnetohydrodynamic (MHD) approach with a detailed two-way coupled treatment of fast electron beams. This allowed breakthroughs on post-flare coronal rain in 2021, ApJL 920, L15, where we simulated from the hottest to the coolest phases in solar coronal settings. Flare related studies with thermal aspects emphasized include our 2023 Solar Physics 298, 134 paper. A high resolution view on a long term coronal rain event was realized in 2022, ApJ 926, 216, where the randomised nature of the heating imposed had clear consequences on the rain evolution, visible in extreme ultraviolet observing channels. We have synthesized spectroscopic views on our high resolution prominence data, reported in 2023, A&A 670, A179. We followed our numerical models far into the turbulent states that actual quiescent prominences achieve, and made direct contact with turbulence studies. Turbulent details in prominence simulations, with clear similarities with observational studies, were demonstrated in 2023, A&A 672, A152. A unique model to show that rotation may be a recurring dynamical ingredient when prominences form was showcased in ApJ Letters, 953, L13 (2023). We studied the oscillatory patterns in multi-dimensional, multi-threaded filaments, this time in fully non-adiabatic evolutions where they form dynamically, and studied how they responded to footpoint disturbances in 2023, A&A 670, A64.
A further major realization has been the development and launch of our open-source linear MHD solver for non-uniform coronal slabs and loops: the state-of-the-art Legolas code (see http://legolas.science/(odnośnik otworzy się w nowym oknie)). In the paper 2020, ApJ Supplement Series 251, 25, we demonstrated that we can reproduce many previous quantifications of the linear MHD eigenmodes in a realistic solar plasma setting. This places the thermal instability in the proper context of the MHD eigenspectrum, and Legolas is an invaluable tool to connect linear MHD studies with nonlinear MPI-AMRVAC simulations, one of the main objectives of our project. A clear demonstration of its potential was given in 2021, Solar Physics 296, 143, where we showed that any realistic solar atmosphere model from chromosphere to corona actually hosts myriads of thermal and magneto thermal instability routes. Follow-up studies extended the physics included: see J. De Jonghe, N. Claes & R. Keppens, 2022, Journal of Plasma Physics 88, 905880321. We identified the oscillatory patterns in multi-dimensional, multi-threaded filaments, and how they respond to sudden energizations (seen as Large Amplitude Oscillations) in 2022, A&A 658, A58. We studied how tearing modes are influenced by flows in 2024, Physics of Plasmas 31, 032106, while we identified how linear MHD wave modes transform in their upward progression through the stratified atmosphere, in the presence of magnetic nulls, in 2024, A&A 681, A43.
Full 3D models of entire prominences featured in D. Donne & R. Keppens, 2024, ApJ 971, 90. A new module to perform frozen-field hydrodynamic models in complex magnetic field topologies was realized in Zhou et al, ApJ 968, 123, 2024. This will be useful for future research beyond the original goals of PROMINENT.
A further major realization has been the development and launch of our open-source linear MHD solver for non-uniform coronal slabs and loops: the state-of-the-art Legolas code (see http://legolas.science/(odnośnik otworzy się w nowym oknie)). In the paper 2020, ApJ Supplement Series 251, 25, we demonstrated that we can reproduce many previous quantifications of the linear MHD eigenmodes in a realistic solar plasma setting. This places the thermal instability in the proper context of the MHD eigenspectrum, and Legolas is an invaluable tool to connect linear MHD studies with nonlinear MPI-AMRVAC simulations, one of the main objectives of our project. A clear demonstration of its potential was given in 2021, Solar Physics 296, 143, where we showed that any realistic solar atmosphere model from chromosphere to corona actually hosts myriads of thermal and magneto thermal instability routes. Follow-up studies extended the physics included: see J. De Jonghe, N. Claes & R. Keppens, 2022, Journal of Plasma Physics 88, 905880321. We identified the oscillatory patterns in multi-dimensional, multi-threaded filaments, and how they respond to sudden energizations (seen as Large Amplitude Oscillations) in 2022, A&A 658, A58. We studied how tearing modes are influenced by flows in 2024, Physics of Plasmas 31, 032106, while we identified how linear MHD wave modes transform in their upward progression through the stratified atmosphere, in the presence of magnetic nulls, in 2024, A&A 681, A43.
Full 3D models of entire prominences featured in D. Donne & R. Keppens, 2024, ApJ 971, 90. A new module to perform frozen-field hydrodynamic models in complex magnetic field topologies was realized in Zhou et al, ApJ 968, 123, 2024. This will be useful for future research beyond the original goals of PROMINENT.
We got detailed answers to our original motivating science questions.
An open conference event on our research topics in Leuven was held from May 21-24: the Coronal Cooling Conference.
An open conference event on our research topics in Leuven was held from May 21-24: the Coronal Cooling Conference.