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1. Modeling CME encounters at Parker Solar Probe with OSPREI: Dependence on photospheric and coronal conditions

   https://doi.org/10.1051/0004-6361/202245445  

   Ledvina, Vincent E.; Palmerio, Erika; Kay, Christina; Al-Haddad, Nada; Riley, Pete (May 2023, Astronomy & Astrophysics)

   Context.Coronal mass ejections (CMEs) are eruptions of plasma from the Sun that travel through interplanetary space and may encounter Earth. CMEs often enclose a magnetic flux rope (MFR), the orientation of which largely determines the CMEs’ geoeffectiveness. Current operational CME models do not model MFRs, but a number of research ones do, including the Open Solar Physics Rapid Ensemble Information (OSPREI) model. Aims.We report the sensitivity of OSPREI to a range of user-selected photospheric and coronal conditions. Methods.We modeled four separate CMEs observed in situ by Parker Solar Probe (PSP). We varied the input photospheric conditions using four input magnetograms (HMI Synchronic, HMI Synoptic, GONG Synoptic Zero-Point Corrected, and GONG ADAPT). To vary the coronal field reconstruction, we employed the Potential Field Source Surface (PFSS) model and varied its source-surface height in the range 1.5–3.0R_⊙with 0.1R_⊙increments. Results.We find that both the input magnetogram and PFSS source surface often affect the evolution of the CME as it propagates through the Sun’s corona into interplanetary space, and therefore the accuracy of the MFR prediction compared to in situ data at PSP. There is no obvious best combination of input magnetogram and PFSS source surface height. Conclusions.The OSPREI model is moderately sensitive to the input photospheric and coronal conditions. Based on where the source region of the CME is located on the Sun, there may be best practices when selecting an input magnetogram to use. 

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2. Estimating Electron Densities in the Middle Solar Corona Using White-light and Radio Observations

   https://doi.org/10.3847/1538-4357/ae4353  

   Mondal, Surajit; Shaik, Shaheda Begum; Howard, Russell A; Zhang_张, Peijin 沛锦; Chen, Bin; Chen, Xingyao; Yu, Sijie; Gary, Dale; Anderson, Marin M; Bowman, Judd D; et al (March 2026, The Astrophysical Journal)

   The electron density of the solar corona is a fundamental parameter in many areas of solar physics. Traditionally, routine estimates of coronal density have relied exclusively on white-light observations. However, these density estimates, obtained by inverting the white-light data, require simplifying assumptions, which may affect the robustness of the measurements. Hence, to improve the reliability of coronal density measurements, it is highly desirable to explore other complementary methods. In this study, we estimate the coronal electron densities in the middle corona, between approximately 1.7 and 3.5R_⊙, using low-frequency radio observations from the recently commissioned Long Wavelength Array at the Owens Valley Radio Observatory (OVRO-LWA). The results demonstrate consistency with those derived from white-light coronagraph data and predictions from theoretical models. We also derive a density model valid between 1.7 and 3.5r_⊙, given by $\rho \left(r^{\prime }\right)=1.27{r{}^{\prime }}^{-2}+29.02{r{}^{\prime }}^{-4}+71.18{r{}^{\prime }}^{-6}$ , where $r^{\prime }=r/R_{\odot }$ , withrthe heliocentric distance. OVRO-LWA is a solar-dedicated radio interferometer that provides science-ready images with low latency, making it well suited for generating regular and independent estimates of coronal densities to complement existing white-light techniques. 

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3. Quantitative Characterization of Magnetic Flux Rope Properties for Two Solar Eruption Events

   https://doi.org/10.3847/1538-4357/ac78df  

   He, Wen; Hu, Qiang; Jiang, Chaowei; Qiu, Jiong; Prasad, Avijeet (July 2022, The Astrophysical Journal)

   Abstract In order to bridge the gap between heliospheric and solar observations of coronal mass ejections (CMEs), one of the key steps is to improve the understanding of their corresponding magnetic structures like the magnetic flux ropes (MFRs). But it remains a challenge to confirm the existence of a coherent MFR before or upon the CME eruption on the Sun and to quantitatively characterize the CME-MFR due to the lack of direct magnetic field measurements in the corona. In this study, we investigate MFR structures originating from two active regions (ARs), AR 11719 and AR 12158, and estimate their magnetic properties quantitatively. We perform nonlinear force-free field extrapolations with preprocessed photospheric vector magnetograms. In addition, remote-sensing observations are employed to find indirect evidence of MFRs on the Sun and to analyze the time evolution of magnetic reconnection flux associated with the flare ribbons during the eruption. A coherent “preexisting” MFR structure prior to the flare eruption is identified quantitatively for one event from the combined analysis of the extrapolation and observation. Then the characteristics of MFRs for two events on the Sun before and during the eruption forming the CME-MFR, including the axial magnetic flux, field line twist, and reconnection flux, are estimated and compared with the corresponding in situ modeling results. We find that the magnetic reconnection associated with the accompanying flares for both events injects a significant amount of flux into the erupted CME-MFRs. 

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4. Synthetic Remote-sensing and In Situ Observations of Fine-scale Structure in a Pseudostreamer Coronal Mass Ejection through the Solar Corona

   https://doi.org/10.3847/1538-4365/adb14e  

   Lynch, B J; Wyper, P F; Palmerio, E; Casillas, L; Dahlin, J T; Daldorff, L_K S; Guidoni, S E; Higginson, A K; Kumar, P; Liberatore, A; et al (March 2025, The Astrophysical Journal Supplement Series)

   Abstract Coronal pseudostreamer flux systems have a specific magnetic configuration that influences the morphology and evolution of coronal mass ejections (CMEs) from these regions. Here we continue the analysis of the Wyper et al. magnetohydrodynamic simulation of a CME eruption from an idealized pseudostreamer configuration through the construction of synthetic remote-sensing and in situ observational signatures. We examine the pre-eruption and eruption signatures in extreme ultraviolet and white light from the low corona through the extended solar atmosphere. We calculate synthetic observations corresponding to several Parker Solar Probe–like trajectories at ∼10R_⊙to highlight the fine-scale structure of the CME eruption in synthetic WISPR imagery and the differences between the in situ plasma and field signatures of flank and central CME-encounter trajectories. Finally, we conclude with a discussion of several aspects of our simulation results in the context of interpretation and analysis of current and future Parker Solar Probe data. 

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5. Evolution of Coronal Mass Ejections in Different Data-driven Solar Wind Conditions

   https://doi.org/10.3847/1538-4357/ae4348  

   Sachdeva, Nishtha; Huang, Zhenguang; Toth, Gabor; Chen, Hongfan; Manchester, Ward B; van_der_Holst, Bart (April 2026, The Astrophysical Journal)

   Abstract Numerical models of the solar wind and coronal mass ejections (CMEs) utilize photospheric magnetic field observations to prescribe the inner boundary conditions for the plasma solutions. These magnetic field data are available to the community through various observational instruments, prepared via different methodologies and/or flux transport models. The solar wind solution driven by these maps provides the ambient plasma environment into which CMEs travel. Interaction with the surrounding solar wind impacts CME evolution and propagation in the solar corona and inner heliosphere. In this work, we use different input magnetic field maps for the same time period to drive the global Alfvén Wave Solar atmosphere Model. We obtain the ambient solar wind conditions and compare the plasma properties and magnetic morphology in the corona domain to study the influence of the input maps. To understand how the resulting coronal solutions impact CMEs, we launch eruptions described by analytical flux ropes into these data-driven solutions and compare their evolution in the coronal domain (up to 24R_⊙radially). The CMEs achieve varying speeds, deceleration rates, propagation directions, mass, and energies while coupling with the background solar wind. We quantify these differences to show that the different input driving maps can significantly impact the simulated CME propagation in the solar wind plasma. This also highlights the importance of understanding the uncertainties associated with data-driven modeling that become increasingly important in operational models and space weather prediction. 

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