Predicting interplanetary coronal mass ejections (ICMEs) remains challenging due to limited datasets, the complexity of some approaches based on machine learning and the continued reliance on manual event validation. We introduce SWAAT (Space Weather Automated Analysis Tool), a framework that integrates automated validation with synthetic data-driven prediction to improve ICME transit time (TT) forecasts based on propagation velocity (Vp). The system comprises two main modules: (i) The Automated Data Acquisition and Analysis (ADAA), which automates ICME candidate validation using GOES X-ray and SDO imagery, and (ii) The Generative-Evolutionary Synthetic Data (GESD), which employs evolutionary algorithms to generate optimized synthetic datasets for model training. By combining automatic event validation with quality synthetic data, SWAAT mitigates the limitations imposed by scarce datasets thanks to the contribution of synthetic data, improving the accuracy of space weather forecasting.

Gamma-ray emission during solar eruptive events is thought to be caused mainly by high-energy (MeV-TeV) protons propagating to the lower layers of the solar atmosphere, i.e. the chromosphere and photosphere, and the subsequent pion production and decay. A potential source of these high-energy particles are coronal mass ejection (CME)-driven shocks, followed by particle back-precipitation to the Sun. Alternatively, a scenario where particles propagate from a compact acceleration site along extended coronal loops towards the emission region is also a possibility. In both cases, the solar magnetic field configuration is a key ingredient to understand the origins of the gamma-ray emission as observed, e.g. by the Fermi Large Area Telescope (LAT). Here, we investigate the propagation of energetic protons and their subsequent gamma-ray production in a comprehensive modeling framework based on the CRPropa code, which is a well-established tool in high-energy astrophysics. The advantage of this approach is that the proton transport and gamma ray production can be studied with a single, unified code by following individual particle trajectories. We present first results of particle dynamics and the resulting gamma-ray distributions based on simplified field structures in a potential field (PFSS) model. We discuss further prospects of our approach that can include outputs from detailed MHD simulations of CME evolution and extensions to other energy regimes.

Using multi-viewpoint observations from STEREO and SOHO during three solar cycles from 23 to 25, we study the magnetic flux rope (MFR) structures of coronal mass ejections (CMEs) near the Sun and magnetic clouds (MCs) at 1au. The study aims to investigate two phenomena: 1) the occurrence rate of CMEs near Hale sector boundaries (HBs) and 2) solar-cycle variation of MFR axial orientations in CMEs and MCs. Our preliminary results include: 1) the axes of MFRs in cycle 25 present a systematic northward orientation, which is the same as in cycle 23 but opposite to cycle 24; 2) the majority of the MFRs occurred near HBs (within 30 degrees) and some exceptional events occurred at non-HBs; 3) the axial fields in MCs present a similar north-south orientation, which changes from cycle to cycle. We discuss the implication of solar cycle variations of MFR axial orientations for space weather forecasts.

Coronal mass ejections (CMEs) play a significant role in space weather. In order to evaluate space weather effects, it is important to understand the origin of CMEs in the solar atmosphere. Among various proxies for CMEs in the low corona, the coronal dimming observed as intensity deficit in extreme ultraviolet (EUV) or soft X-ray wavelengths is thought to be the most reliable observable. We examine dimmings detected automatically by Solar Demon in images taken by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO), and associate strong dimmings with CMEs, flares and EUV waves. The association rate of dimmings with either CMEs or flares is about 75%, and that with EUV waves is about 35%. We also discuss the complementary use of EUV irradiance data, for example, from the Extreme Ultraviolet Experiment on board SDO to isolate dimmings. This may have implications in detecting CMEs from stars.

In this contribution to the panel discussion of the IAU Symposium Nº 388 “Solar and Stellar Coronal Mass Ejections”, I concentrate on white-light observations of solar coronal mass ejections (CMEs) from space and specifically address the following aspects: i) history of observations, ii) available catalogs of CMEs, iii) achievements of space observations of CMEs, iv) future of CME observation, and v) challenges and future directions.

Coronal mass ejections (CMEs) have been suggested to be the source of high-energy protons producing sustained gamma-ray emission (SGRE) events at the Sun, where the >100 MeV gamma-ray emission observed by Fermi Large Area Telescope (LAT) lasts beyond the end of the associated X-ray flare. Large SEP events observed at 1 au are produced by shocks driven by fast and wide (FW) CMEs. However, there are more large SEP events than SGRE events and more FW CMEs than the large SEP events. Magnetic connectivity of the observer to the shock nose affects the detectability of SEP events at 1 au. [Makela et∼al., 2023] found that the SGRE-producing halo CMEs associated with type II radio bursts and/or a large SEP events have higher space speeds and initial accelerations than those without an SGRE event. In this paper, we consider characteristics of CME eruptions associated with co-occurring SEP and SGRE events.

This paper provides an update on the coronal mass ejection (CME) catalog maintained at the CDAW Data Center, NASA Goddard Space Flight Center (http://cdaw.gsfc.nasa.gov/CME_list). This is version 2 (v2) of the Catalog that has been made as the default version as of May 1, 2024. The new features of the Catalog v2 are (i) online measurement tool, (ii) combination JavaScript movies from the STEREO and Solar Dynamics Observatory (SDO) missions, and (iii) insertion of newly identified CMEs for the period 1996 to 2004. The CME identification was revisited resulting in a set of ∼3000 new CMEs added to the Catalog. A vast majority of these CMEs are weak and narrow. The resulting statistical properties of CMEs are not significantly different from those reported using version 1.

Solar type-II radio bursts are coherent plasma emissions arising from magnetohydrodynamic shocks produced by either coronal mass ejections (CMEs) or flares. Type-II bursts sometimes show split-band emissions in the dynamic spectrum. When these split-band emissions come from regions just upstream and downstream of the shock, type-II band-splitting can be used as an important tool for estimating magnetic fields at the shock front. Earlier studies have shown that only ∼20% of the type-IIs show morphologically similar split-bands. Imaging studies can unambiguously identify such instances, though they remain very rare. Here we suggest a useful approach to augment dynamic spectra based studies by also examining the Gradient Dynamic Spectra (GraDS) of type-II emission. We also verified the conclusions of this approach against those from an imaging study.

Coronal mass ejections (CMEs) are large-scale ejections of magnetized plasma from the Sun and are associated with the most extreme space weather events. The southward component of CME magnetic fields (CME-Bz) is one of the crucial parameters determining its geoeffectiveness. Recent studies have shown that CMEs evolve significantly in the innermost part of the heliosphere (∼ 20 − 90 R⊙), and relying on extrapolations from low coronal heights can lead to wrong predictions of CME-Bz in the vicinity of Earth. Hence, measuring CME magnetic fields at these heights is important to improve CME-Bz prediction. A promising method to measure the CME-entrained magnetic field in the larger coronal heights and the innermost heliosphere is by measuring the changes in Faraday rotation (FR) of linearly polarized emission from back-ground radio sources as their line-of-sight crosses the CME plasma. Here, we present the current preparation of new-generation ground-based radio telescopes for this purpose.

We analyses occurrence of DH type II solar radio bursts spanning over solar cycles 23-25 during which a total of 590 DH type II bursts are reported with confirmed 568 and 462 cases of associated CME and flares, respectively. We find short-term yet important differences in DH type II activity when the data is examined in terms of event counts and their durations, e.g., temporal shift in the peak activity during cycle 24 and variation in the growth rate of the activity level during cycle 25. For an in-depth exploration, DH type II bursts are classified in 3 categories based on their end-frequencies: Low-, Medium-, and High- Frequency Groups (LFG, MFG, and HFG, respectively). The HFG category is the most populous (≈47%) while the LFG category occupy about a quarter of the events (≈24%). The LFG events show a clear inclination toward fastest CMEs and X-class flares with a quarter of events exhibiting end frequency below 50 MHz.

Eruptive and confined flares are distinguished by their coronal mass ejection (CME) association. From 1996 January to 2023 December, we found 1,748 flares with definite CME association (eruptive flares) and 7,288 flares that lacked CMEs (confined flares) using the coronagraph observations by SOHO/LASCO and STEREO/SECCHI. Flare temperatures, which are measured from the GOES short/long wavelength ratio, increase with the peak X-ray intensity. Average maximum temperature is 10 MK at C3.0 and 24 MK at X10 level. [Kay et∼al., 2003] examined a total of 69 eruptive and confined flares and found that eruptive flares tend to have lower temperatures than the confined ones. By analyzing a 100 times larger data set, we confirmed that result and found that, for a given X-ray flare intensity, the average maximum temperature of eruptive flares is approximately 0.9 MK cooler than that of the confined ones.

Recent research has revealed that small-scale coronal mass ejections (CMEs) in the quiet Sun exhibit similarities in their formation mechanisms and eruption characteristics when compared to large-scale solar eruptions. The occurence of small-scale CMEs increases exponentially as their size decreases. Thus, the role of small-scale CMEs in solar wind formation should not be underestimated. Can small-scale eruptions in the quiet Sun propagate into the higher solar corona? I analyze a typical small-scale eruption in the quiet Sun and reconstruct a flux-rope (FR) structure. My results indicate that torus instability of the FR can be triggered at a relatively low critical height of : 8 Mm. This suggests that the quiet Sun’s FRs can easily overcome the confinement of the low coronal magnetic field and enter the higher corona. However, further investigation is still needed to determine if the large-scale coronal mangetic fields above constrain these small-scale eruptions.

We assess the relative strength of solar cycle (SC) 25 with respect to SCs 23 and 24 based on the abundance of halo coronal mass ejections (CMEs). We make use of the halo CME database (https://cdaw.gsfc.nasa.gov/CME_list/halo/halo.html) to compare the halo CME abundance during the first four years in each of SCs 23–25. The main result is that in several aspects such as the abundance, occurrence rate, source locations, and halo heights, halo CMEs are similar between SCs 24 and 25 but different from SC 23. This result follows from the fact that weaker cycles have low heliospheric total pressure, whose backreaction on CMEs allows them to expand more and hence enhancing the chance of becoming a halo. The solar cycle variation of halo CME properties is consistent with the precursor-based cycle prediction methods that indicate SC 25 is similar to or only slightly stronger than SC 24.

Shocks driven by coronal mass ejections (CMEs) are primary drivers of gradual solar energetic particle (SEP) events, posing significant risks to space technology and astronauts. Concurrently, particles accelerated at these shocks may also propagate back to the Sun, potentially generating gamma-ray emissions through pion decay. We incorporated advanced modeling and multi-messenger observations to explore the role of CME-driven shocks in gamma-ray emissions and SEPs. Motivated by Fermi-LAT long-duration solar flares, we used the AWSoM MHD model to investigate the connection between the shocks and the properties of observed gamma-ray emissions. By coupling the AWSoM with iPATH model, we evaluate the impact of shock evolution complexity near the Sun on SEP intensity and spectra. Our result points to the importance of accurate background coronal and solar wind modeling, as well as detailed observations of CME source regions, in advancing our understanding of CME-driven shocks and the dynamics of associated energetic particles.

Generally Coronal Mass Ejections (CMEs) are large eruptions of plasma and magnetic field from the Sun into interplanetary space. CMEs are most frequently associated with a variety of phenomena occurring in the lower corona before, during and after onset of eruption and generally are visible in coronagraph observation. Stealth CMEs do not obviously exhibit any of the low-coronal signatures (LCS) like solar flares, flows, jets, coronal dimmings or brightenings, filament eruptions or the formation of flare loop arcades. In this study, five stealth CMEs are selected using LASCO/SOHO CME catalogue and associated ICMEs (Interplanetaty CMEs) are identified using data from STEREO, ACE and WIND.

An onboard automated coronal mass ejections (CMEs) detection algorithm has been developed for Visible Emission Line Coronagraph (VELC) onboard ADITYA-L1. The aim of this algorithm is to reduce the load on telemetry by sending the high spatial (~ 2.51 arcsec pixel−1) and temporal (1 s) resolution images of corona from 1.05 R⊙ to 3 R⊙, containing CMEs and rejecting others. It is based on intensity thresholding followed by an area thresholding in successive running difference images which are re-binned to lower resolution to improve signal to noise. Here we present the results of application of the algorithm on synthetic corona images generated for the VELC field of view (FOV).

We have studied the consequences of interacting coronal mass ejections (CMEs) of June 13-14, 2012 which were directed towards Earth and caused a moderate geomagnetic storm with Dst index ~ −86 nT. We analysed the in-situ observations of the solar wind plasma and magnetic field parameters obtained from the OMNI database for these CMEs. The in-situ observations show that the interacting CMEs arrive at Earth with the strongest (~ 150 nT) Sudden Storm Commencement (SSC) of the solar cycle 24. We compared these interacting CMEs to a similar interaction event which occurred during November 9-10, 2012. This occurred in the same phase of the solar cycle 24 but resulted in an intense geomagnetic storm (Dst ~ −108 nT), as reported by Mishra et al. (2015). Our analysis shows that in the June event, the interaction led to a merged structure at 1 AU while in the case of November 2012 event, the interacted CMEs arrived as two distinct structures at 1 AU. The geomagnetic signatures of the two cases reveal that both resulted in a single step geomagnetic storm.

Because of the significant dangers they pose, accurate forecasting of Solar Energetic Particle (SEP) events is vital. Whilst it has long been known that SEP-production is associated with high-energy solar events, forecasting algorithms based upon the observation of these types of solar event suffer from high false alarm rates. Here we analyse the parameters of 4 very high energy solar events which were false alarms, with a view to reaching an understanding as to why SEPs were not detected at Earth. We find that in each case at least two factors were present which have been shown to be detrimental to SEP production.

Visible Emission Line Coronagraph (VELC) on board ADITYA-L1 is an internally occulted coronagraph with mirror as its primary objective element. It has a field of view (FOV) starting from 1.05 R⊙ – 3 R⊙. It will observe the corona in continuum centered at 5000 Å and will perform spectroscopic observations of inner corona in two visible (5303 Å and 7892 Å) and one infrared (10747 Å) wavelengths. VELC will be capable of observing the corona with high spatial and temporal resolutions. We present an overview of the inner coronagraph (VELC) design and introduce the concept of an on-board automated coronal mass ejections (CMEs) detection logic proposed for this payload.

The magnetic breakout model has been widely used to explain solar eruptive activities. Here, we apply it to explain successive filament eruptions occurred in a quadrupolar magnetic source region. Based on the high temporal and spatial resolution, multi-wavelengths observations taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO), we find some signatures that support the occurrence of breakout-like external reconnection just before the start of the successive filament eruptions. Furthermore, the extrapolated three-dimensional coronal field also reveals that the magnetic topology above the quadrupolar source region resembles that of the breakout model. We propose a possible mechanism within the framework of the breakout model to interpret the successive filament eruptions, in which the so-called magnetic implosion mechanism is firstly introduced to be the physical linkage of successive filament eruptions. We conclude that the structural properties of coronal fields are important for producing successive filament eruptions.