A list of the previously discussed papers can be found here .
White-light observations from the WISPR instrument on NASA's Parker Solar Probe recently revealed the presence of a narrow, dense dust trail close to the orbit of asteroid 3200 Phaethon. Although Geminid-related, it aligns imperfectly with Phaethon's orbit and known Geminid meteoroid orbits. To address the nature of this dust trail, we performed a detailed comparison between the WISPR trail observations and several well-developed Geminid models. Simulating these models in the WISPR field of view visually demonstrates that the WISPR trail almost certainly represents the true ``density core'' of the Geminid stream. Trends in model trail width and offset from Phaethon's orbit, both as functions of true anomaly, agree with observations to varying extents. All the models, however, place their apparent core interior to the parent orbit due to Poynting-Robertson forces, contradictory to the WISPR trail which is exterior to Phaethon's orbit. Therefore, Phaethon's current orbit likely does not represent the orbit of the system parent, which most probably had a larger semi-major axis. These findings provide new initial conditions for future Geminid models, with WISPR identifying the Geminid core's position.
Magnetic reconnection is a key process that drives the energy release in solar flares. This process can occur at multiple locations along the coronal loop. The reconnection generates energetic electrons capable of exciting wave modes and emissions as they propagate through the loop. In this follow-up study, we investigate the influence of the injection site location of these energetic electrons - either at the looptop (LT) or at the leg of the loop around a footpoint (FP) - on the excitation of wave modes especially the second harmonic emissions (X2) in coronal loops. Our simulations reveal that the injection location significantly impacts the spatial distribution and intensity of excited wave modes. When electrons are injected at the LT, electromagnetic X2, and Z modes dominate along the loop, with minimal excitation of Langmuir waves (Yousefzadeh et al. 2021; 2022). Conversely, the present study reveals that injection close to FP leads to a strong Langmuir wave excitation throughout the loop, particularly as electrons ascend toward the LT. We find that X2 and Z modes are consistently excited at the injection site with different intensities, regardless of the injection location. However, electron injection near the FP scenario creates favorable conditions for significant Langmuir wave generation, potentially leading to plasma emission under specific circumstances. These findings emphasize the importance of electron injection location in determining the properties of the excited and emitted waves in solar coronal loops.