arXiv subjects

Diego G. Lloveras

Publications and source records attributed to Diego G. Lloveras.

3 recordsLinked to original sources

arXiv2026

Characterizing the Martin Luther King Event: Sun to Earth Evolution of the January 19, 2026 Geomagnetic Storm

We present a comprehensive Sun-to-Earth analysis of the extreme space weather event of 18 -19 January 2026, hereafter the Martin Luther King (MLK) storm, which produced a severe (G4) geomagnetic storm and one of the most intense solar radiation storms of Solar Cycle 25. The geomagnetic disturbance was driven by a fast Earth-directed coronal mass ejection (CME) associated with an X1.9-class flare from NOAA Active Region 14341. We combine multi-viewpoint remote-sensing observations, in situ measurements from Solar Orbiter and Wind, and physics-based magnetohydrodynamic simulations using the CORHEL-CME framework to reconstruct the eruption from the low corona to 1 au and identify the mechanisms governing its geoeffectiveness. Observations and simulations indicate that the eruption originated from a right-handed magnetic flux rope embedded in a complex magnetic environment dominated by a neighboring positive-polarity coronal hole. The simulations reproduce the observed CME morphology, asymmetric expansion, magnetic fields measured at both spacecraft, and Dst index evolution. The main discrepancy is attributed to filament material not included in the model. Favorable magnetic polarity alignment between the CME and coronal-hole field minimized magnetic erosion through interchange reconnection, enabling rapid escape and preservation of the strong southward magnetic field that drove the geomagnetic storm. The prolonged recovery phase resulted from interaction between the trailing CME and a following high-speed stream from the same coronal hole. These results demonstrate that storm intensity was primarily established by the coronal magnetic configuration, whereas storm duration was controlled by the ambient solar wind.

astro-ph.SR↗

arXiv2026

Automatic detection of CMEs using synthetically-trained Mask R-CNN

Coronal mass ejections (CMEs) are a major driver of space weather. To assess CME geoeffectiveness, among other scientific goals, it is necessary to reliably identify and characterize their morphology and kinematics in coronagraph images. Current methods of CME identification are either subjected to human biases or perform a poor identification due to deficiencies in the automatic detection. In this approach, we have trained the deep convolutional neural model Mask R-CNN to automatically segment the outer envelope of one or multiple CMEs present in a single difference coronagraph image. The empirical training dataset is composed of 10^5 synthetic coronagraph images with known pixel-level CME segmentation masks. It is obtained by combining quiet coronagraph observations, with synthetic white-light CMEs produced using the GCS geometric model and ray-tracing technique. We found that our model-based trained Mask R-CNN infers segmentation masks that are smooth and topologically connected. While the inferred masks are not representative of the detailed outer envelope of complex CMEs, the neural model can better differentiate a CME from other radially moving background/foreground features, segment multiple simultaneous CMEs that are close to each other, and work with images from different instruments. This is accomplished without relying on kinematic information, i.e. only the included in the single input difference image. We obtain a median IoU=0.98 for 1.6*10^4 synthetic validation images, and IoU=0.77 when compared with two independent manual segmentations of 115 observations acquired by the COR2-A, COR2-B and LASCO C2 coronagraphs. The methodology presented in this work can be used with other CME models to produce more realistic synthetic brightness images while preserving desired morphological features, and obtain more robust and/or tailored segmentations.

astro-ph.SR↗

arXiv2025

Partial Null Point Reconnection of an Eruptive Filament

Solar filaments are cool and dense plasma structures suspended in the solar corona against gravity. We present observations of a quiescent filament eruption that occurs on 13 July 2015. The eruption is associated with a two-ribbon GOES B8.9 class flare. Photospheric magnetic flux cancellation is present below the filament during days. This builds up a flux rope which progressively rises until it gets unstable, first leading to a confined eruption and pre-flare brightenings, then to an ejection which starts $\approx$ 20 min later with the flare onset. An interesting feature of this event is the presence of a large circular brightening formed around the erupting region. This brightening is produced due to interchange reconnection of the ejected magnetic configuration with the surrounding open magnetic field. This null-point topology is confirmed by a potential-field extrapolation. The EUV loops located on the southern side of the filament eruption first contract during the null-point reconnection, then expand as the flux rope is ejected. The associated CME has both a classical flux rope shape and plasma ejected along open field lines on the flux rope side (a trace of interchange reconnection). Finally, we set all this disparate observations within a coherent framework where magnetic reconnection occurs both below and above the erupting filament.

astro-ph.SR↗