nicolapo

• Lomazzi, Paul; Rouillard, Alexis P.; Lavarra, Michael A.; Poirier, Nicolas Aurelien Corentin; Blelly, Pierre-Louis & Dakeyo, Jean-Baptiste [Vis alle 10 forfattere av denne artikkelen] (2025). A Parametric Study of Solar Wind Properties and Composition Using Fluid and Kinetic Solar Wind Models. The Astrophysical Journal (ApJ). ISSN 0004-637X. 984(2). doi: 10.3847/1538-4357/adc2f6. Fulltekst i vitenarkiv Vis sammendrag

  The physical processes in the solar corona that shape the solar wind remain an active research topic. Modeling efforts have shown that energy and plasma exchanges near the transition region play a crucial role in modulating solar wind properties. Although these regions cannot be measured in situ, plasma parameters can be inferred from coronal spectroscopy and ionization states of heavy ions, which remain unchanged as they escape the corona. We introduce a new solar wind model extending from the chromosphere to the inner heliosphere, capturing thermodynamic coupling across atmospheric layers. By including neutral and charged particle interactions, we model the transport and ionization processes of the gas through the transition region and corona and into the solar wind. Instead of explicitly modeling coronal heating, we link its spatial distribution to large-scale magnetic field properties. Our results confirm that energy deposition strongly affects wind properties through key mechanisms involving chromospheric evaporation, thermal expansion, and magnetic flux expansion. For sources near active regions, the model predicts significant solar wind acceleration, with plasma outflows comparable to those inferred from coronal spectroscopy. For winds from large coronal holes, the model reproduces the observed anticorrelation between charge state and wind speed. However, the predicted charge state ratios are overall lower than observed. Inclusion of a population of energetic electrons enhances both heavy ion charge states and solar wind acceleration, improving agreement with observations.

• Poirier, Nicolas Aurelien Corentin; Danilovic, S.; Kohutova, Petra; Baso, Carlos José Díaz; Voort, Luc Rouppe van der & Calchetti, D. [Vis alle 7 forfattere av denne artikkelen] (2025). Coronal kink oscillations and photospheric driving: Combining SolO/EUI and SST/CRISP high-resolution observations. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 696. doi: 10.1051/0004-6361/202453025. Fulltekst i vitenarkiv Vis sammendrag

  Context. The driving and excitation mechanisms of decay-less kink oscillations in coronal loops remain under active debate. The photospheric dynamics may provide the continuous energy supply required to sustain these oscillations. Aims. We aim to quantify and provide simple observational constraints on the photospheric driving of coronal loops in a few typical active region configurations: sunspot, plage, pores, and enhanced-network regions. We then aim to investigate the possible interplay between the photospheric driving and the properties of kink oscillations in the connected coronal loops. Methods. We analysed two unique datasets of the corona and photosphere taken at a high spatial and temporal resolution during the first coordinated observation campaign between Solar Orbiter and the Swedish 1-m Solar Telescope (SST). We applied a local correlation tracking method on the SST/CRISP data to quantify the photospheric motions at the base of coronal loops. The same loops were then analysed in the corona by exploiting data from the Extreme Ultraviolet Imager (EUI) on Solar Orbiter and by using a wavelet analysis to characterise the detected kink oscillations. Results. Each type of photospheric region shows varying dynamics but with an overall increase in strength going from pore to plage to enhanced-network to sunspot regions. Differences can also be seen in the amplitudes of the fundamental kink mode measured in the corresponding coronal loops. This suggests the photosphere is involved in the driving of coronal kink oscillations. However, the few samples available do not allow the excitation mechanism to be further established yet. Conclusions. Despite oscillating coronal loops being anchored in seemingly “static” strong magnetic field regions, as seen from coronal EUV observations, photospheric observations provide evidence for a continuous and significant driving at their base. The precise connection between photospheric driving and coronal kink oscillations remains to be further investigated. Upcoming coordinated observations between Solar Orbiter and ground-based telescopes will provide crucial additional observational constraints, with this pilot study serving as a baseline for future works. Finally, this study provides critical constraints on both the quasi-steady and broadband photospheric driving that can be tested in existing numerical models of coronal loops.

• Kohutova, Petra; Antolin, Patrick; Szydlarski, Mikolaj & Poirier, Nicolas Aurelien Corentin (2024). Can we rely on EUV emission to identify coronal waveguides? Astronomy and Astrophysics (A & A). ISSN 0004-6361. 690. doi: 10.1051/0004-6361/202451196. Fulltekst i vitenarkiv Vis sammendrag

  Context. Traditional models of coronal oscillations rely on a modelling of the coronal structures that support them as compact cylindrical waveguides. An alternative model of the structure of the corona has recently been proposed, in which the thin strand-like coronal loops, that are observed in the extreme-UV (EUV) emission are the result of the line-of-sight integration of warps in more complex coronal structures. This is referred to as the coronal veil model. Aims. We extend the implications of the coronal veil model of the solar corona to models of coronal oscillations. Methods. Using convection-zone-to-corona simulations with the radiation-magnetohydrodynamics (rMHD) code Bifrost, we analysed the structure of the self-consistently formed simulated corona. We focused on the spatial variability of the volumetric emissivity of the Fe IX 171.073 Å EUV line and on the variability of the Alfvén speed, which captures the density and magnetic structuring of the simulated corona. We traced features associated with large magnitudes of the Alfvén speed gradient, which trap MHD waves and act as coronal waveguides. We searched for the correspondence with emitting regions, which appear as strand-like loops in the line-of-sight-integrated EUV emission. Results. We find that the cross sections of the waveguides bounded by large Alfvén speed gradients become less circular and more distorted with increasing height in the solar atmosphere. The waveguide filling factors corresponding to the fraction of the waveguides filled with plasma that emits in the given EUV wavelength range from 0.09–0.44. This suggests that we can only observe a small fraction of the waveguide. Similarly, the projected waveguide widths in the plane of the sky are several times larger than the widths of the apparent loops that are observed in the EUV. Conclusions. We conclude that the coronal veil structure is independent of the model. As a result, we find a lack of straightforward correspondence between peaks in the integrated emission profile that constitute apparent coronal loops and regions of plasma bound by a large Alfvén speed gradient that act as waveguides. Coronal waveguides cannot be reliably identified based on emission in a single EUV wavelength is not reliable in the simulated corona formed in convection-zone-to-corona models.

• Réville, Victor; Poirier, Nicolas Aurelien Corentin; Kouloumvakos, Athanasios; Rouillard, Alexis Paul; Pinto, Rui Ferreira & Fargette, Naïs [Vis alle 11 forfattere av denne artikkelen] (2023). HelioCast: heliospheric forecasting based on white-light observations of the solar corona. Journal of Space Weather and Space Climate. 13. doi: 10.1051/swsc/2023008. Fulltekst i vitenarkiv Vis sammendrag

  We present a new 3D magnetohydrodynamic (MHD) heliospheric model for space-weather forecasting driven by boundary conditions defined from white-light observations of the solar corona. The model is based on the MHD code PLUTO, constrained by an empirical derivation of the solar wind background properties at 0.1 au. This empirical method uses white-light observations to estimate the position of the heliospheric current sheet (HCS). The boundary conditions necessary to run HelioCast are then defined from pre-defined relations between the necessary MHD properties (speed, density, and temperature) and the distance to the current sheet. We assess the accuracy of the model over six Carrington rotations during the first semester of 2018. Using point-by-point metrics and event-based analyses, we evaluate the performances of our model varying the angular width of the slow solar wind layer surrounding the HCS. We also compare our empirical technique with two well-tested models of the corona: Multi-VP and WindPredict-AW. We find that our method is well-suited to reproduce high-speed streams, and does – for well-chosen parameters – better than full MHD models. The model shows, nonetheless, limitations that could worsen for rising and maximum solar activity.

• Poirier, Nicolas Aurelien Corentin; Réville, Victor; Rouillard, Alexis P.; Kouloumvakos, Athanasios & Valette, Emeline (2023). Variability of the slow solar wind: New insights from modelling and PSP-WISPR observations. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 677. doi: 10.1051/0004-6361/202347146. Fulltekst i vitenarkiv Vis sammendrag

  Aims. We analyse the signature and origin of transient structures embedded in the slow solar wind, and observed by the Wide-Field Imager for Parker Solar Probe (WISPR) during its first ten passages close to the Sun. WISPR provides a new in-depth vision on these structures, which have long been speculated to be a remnant of the pinch-off magnetic reconnection occurring at the tip of helmet streamers. Methods. We pursued the previous modelling works of Réville et al. (2020, ApJ, 895, L20; 2022, A&A, 659, A110) that simulate the dynamic release of quasi-periodic density structures into the slow wind through a tearing-induced magnetic reconnection at the tip of helmet streamers. Synthetic WISPR white-light (WL) images are produced using a newly developed advanced forward modelling algorithm that includes an adaptive grid refinement to resolve the smallest transient structures in the simulations. We analysed the aspect and properties of the simulated WL signatures in several case studies that are typical of solar minimum and near-maximum configurations. Results. Quasi-periodic density structures associated with small-scale magnetic flux ropes are formed by tearing-induced magnetic reconnection at the heliospheric current sheet and within 3 − 7  R ⊙ . Their appearance in WL images is greatly affected by the shape of the streamer belt and the presence of pseudo-streamers. The simulations show periodicities on ≃90 − 180 min, ≃7 − 10 h, and ≃25 − 50 h timescales, which are compatible with WISPR and past observations. Conclusions. This work shows strong evidence for a tearing-induced magnetic reconnection contributing to the long-observed high variability of the slow solar wind.

Se alle arbeider i NVA

• Poirier, Nicolas Aurelien Corentin (2026). Et strålende samarbeid. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin (2024). Challenges in modelling (coronal) abundances and observational needs. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Kohutova, Petra; Voort, Luc Rouppe van der & Danilovic, Sanja (2024). About the source of sustained kink oscillations in coronal loops. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin (2024). About the enigmatic origin of the (slow) solar wind. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Rouillard, Alexis Paul; Blelly, P.-L.; Lavarra, Michael & Indurain, Mikel (2024). High-order multi-fluid 1D modeling of coronal loops: in-depth look at heavy element abundances. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Kohutova, Petra; Voort, Luc Rouppe van der & Danilovic, Sanja (2024). Photospheric driving of sustained kink oscillations in coronal loops. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Kohutova, Petra; Voort, Luc Rouppe van der & Danilovic, Sanja (2024). About the source of sustained kink oscillations in coronal loops. Fulltekst i vitenarkiv
• Kohutova, Petra; Antolin, Patrick; Szydlarski, Mikolaj & Poirier, Nicolas Aurelien Corentin (2024). Can we rely on EUV emission to identify coronal waveguides? Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Rouillard, Alexis Paul; Blelly, P.-L.; Lavarra, Michael & Indurain, Mikel (2024). Investigating the role of diffusion effects in the fractionation of minor elements in solar loops: using a high-order and multi-specie 1-D model. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Rouillard, Alexis Paul; Réville, Victor; Kouloumvakos, Athanasios & Valette, Emeline (2024). Variability of the slow solar wind: New insights from modelling and PSP-WISPR observations. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Voort, Luc Rouppe van der; Kohutova, Petra & Danilovic, Sanja (2024). About the nature of sustained kink oscillations in coronal loops: combining coronal and chromospheric diagnostics. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Rouillard, Alexis Paul; Lavarra, Michael; Blelly, P.-L.; Indurain, Mikel & Réville, Victor [Vis alle 10 forfattere av denne artikkelen] (2023). On the modelling of multi-specie plasmas: theory and challenges for the solar atmosphere. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin (2023). On the modelling of multi-specie plasmas: theory and challenges for the solar atmosphere. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Rouillard, Alexis Paul; Réville, Victor; Indurain, Mikel & Alexandre, Matthieu (2023). Tutorial on Connectivity Science using the Connectivity-Tool. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Rouillard, Alexis Paul; Kouloumvakos, Athanasios; Réville, Victor & Valette, Emeline (2023). On the variability of the slow solar wind: New insights from the modelling and PSP-WISPR observations. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Kohutova, Petra; Joshi, Reetika & Voort, Luc Rouppe van der (2023). About the source of sustained kink oscillations in coronal loops: what do we know and what do we need from future observation campaigns? Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Lavarra, Michael; Rouillard, Alexis Paul; Blelly, P.-L.; Indurain, Mikel & Réville, Victor (2023). Investigating the role of diffusion effects in the fractionation of minor elements in solar loops, using a multi-specie high-order 1-D model. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Réville, Victor; Rouillard, Alexis; Kouloumvakos, Athanasios; Pinto, Rui F. & Griton, Léa (2022). The (possible) origin of streamer blobs observed by PSP-WISPR. Fulltekst i vitenarkiv

Se alle arbeider i NVA