A fast halo CME and correspondingly strong solar burst that occurred in NOAA9684 led to intense geo-effectiveness. The analysis and study in this paper were focused on the evolution of this active region.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Conventionally coronal mass ejections (CMEs) are categorized into flare-associated and filament-associated types. Since there are also many CMEs of the overlapping type, we classify CMEs into three types in order to compare their characteristics. It is found that the three types of CMEs have quite similar distributions of apparent speeds, with small difference in the average speeds.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Based on the dynamics of charged particles in plasma with the two-fluid description, the equation for magnetic field generation and maintenance is derived. The nature of magnetic field in cosmic plasma and the generation can be understood from the equation. The ions and electrons are considered as two independent fluids with the collision connected. Due to the different viscosity between ions and electrons, there will be a velocity difference in ions and electrons. This causes a current in the plasma and generates magnetic field. IN the plasma system, the differential velocities and the viscous forces of the electrons are the source of magnetic field.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

To examine the stray light in magnetograph observations, we determined the point spread function of the Video Vector Magnetograph mounted on the Solar Magnetic Field Telescope (SMFT) installed at the Huairou Solar Observing Station (HSOS). Then we obtained the curve on large-spread-angle (LSA) stray light intensity as a function of distance from disk center. A new way to correct LSA stray light is proposed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Heliospheric models of Coronal Mass Ejection (CME) propagation and evolution provide an important insight into the dynamics of CMEs and are a valuable tool for interpreting interplanetary in situ observations. Moreover, they represent a virtual laboratory for exploring conditions and regions of space that are not conveniently or currently accessible by spacecraft. In this review I summarize recent advances in modeling the properties and evolution of CMEs in the solar wind. In particular, I will focus on: (1) the types of ICME models; (2) the boundary conditions that are imposed; (3) the role of the ambient solar wind; (4) predicting new phenomena; and (5) distinguishing between competing CME initiation mechanisms. I will conclude by discussing what topics will likely be important for models to address in the future.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Using the observations of LASCO aboard SOHO in the interval from Mar. 1997 to Dec. 2003, 301 earth-directed halo CMEs are selected and the source regions are located in MDI synoptic charts. A statistical analysis has been made with the emphasis on the CMEs' large-scale source regions as well as the correlation between CMEs and solar surface activity. The statistics show that CMEs are intrinsically related to surface activity. Four groups of CMEs' large-scale source structures are identified on the photosphere. They are: I, Extended bipole regions (EBRs) with long magnetic neutral line; II, Closely packed active regions (ARs); III, Large-scale magnetic flux of the same polarity runs through the opposite hemisphere, along the boundary there appears transequatorial filaments; IV, Between two EBRs with long filament. The result shows that CME-associated source activity is closely related to the types of large-scale magnetic structures.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Gradual solar energetic particle (SEP) events are now believed to be associated with CME-driven shocks. As the shock propagates out from the Sun, particles are accelerated diffusively at the shock front and some will escape upstream and downstream into the interplanetary medium. This is in contrast with “impulsive” events, which are believed to be due to solar flares. However, recent observations have found that in some gradual SEP events, the time intensity profile show a two peak feature, suggesting a mixture of particles from solar flares with particles from CME-driven shock. Furthermore, the observed spectra of large SEP events show tremendous variability. The $Fe/C$ ($Fe/O$) ratio behave oppositely in events which have similar solar progenitors. In this work, we use a numerical model to follow particle acceleration and transport at CME-driven shocks. We investigate a possible scenario for the re-acceleration of flare particles by CME-driven shocks and calculate the $Fe/O$ ratio for two exemple shocks. These simulations are helpful in interpreting observations of particle data obtained in situ at 1 AU by spacecraft such as ACE and WIND.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We describe a study of the compositional properties of heliospheric ICME ejecta within the context of solar CME observations. In this study, we examine CME-ICME pairs with an associated flare. For each of these pairs several in situ quantities are averaged over the event and compared with flare magnitude. We find that Mg/O, He/O, and He/H are clearly correlated with flare magnitude suggesting that larger flares provide the CMEs with increased access to the low corona. We also find flare magnitude is positively correlated with velocity and negatively correlated with density, indicating that CMEs which are related to large flares are more likely to experience over-expansion during their propagation to 1 AU.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A distinct coronal inflow has been discovered after $\sim90\,{\rm min}$ of prominence eruption associated coronal mass ejection (CME) on 05-Mar-2000 by EIT (Extreme ultraviolet Imaging Telescope) aboard SoHO (Solar and Heliospheric Observatory). Evolution of the prominence seen by EIT was tracked into the LASCO/C2 and C3 field-of-view (FOV; $4{-}10 R_{\odot}$) where it developed as the core of a typical three-part CME. The speed of the inflow, which was only seen in EIT FOV, was 70-80 km/s at a height between 1.5-1.2 $R_{\odot}$ coinciding with the deceleration phase of the core of the CME in LASCO/C2. In contrast to dark inflow structures observed earlier and interpreted as plasma void moving down, the inflow reported here was bright. The inflow showed a constant deceleration and followed a curved path suggesting the apex of a contracting magnetic loop sliding down along other field linesTo search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

By using the observations of the Extreme-UV Imaging Telescope (EIT), we studied three major solar eruptions from the same super active region NOAA 10486 during the interval of October 26 to November 04, 2003. The three eruptions took place when the active region located on the eastern hemisphere, near the central meridian and on the western limb, respectively. In the first event (Oct 26 event), the coronal disturbance (indicated as an EIT wave) in EUV images was limited east to the central meridian, and there were no solar energetic particles (SEPs) detected. The second event (Oct 28 event) accompanied a nearly entire disk disturbance and very large and prompt SEP enhancements. For the last event (Nov 04 event), there was no obvious coronal disturbance on the disk, and the SEP enhancements were much more gradual. From these observational features, we suggest that different coronal disturbances correspond to different acceleration and propagation histories. A large-scale, cross-disk coronal disturbance may open quite a lot of magnetic field lines in the low corona, facilitating the direct access of flare accelerated SEPs to the Sun-Earth connected interplanetary magnetic field lines. Subsequently the SEP intensity will exhibit a very prompt enhancement.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A distinctive characteristic of interplanetary magnetic clouds is their rope-like magnetic structure, i.e., their smoothly-varying helical field lines whose pitch increases from their core to their boundary. Because this regular structure helps to make MCs particularly geo-effective, it is important to understand how it arises.

We discuss recent work which relates the magnetic and topological parameters of MCs to associated solar active regions. This work strongly supports the notion that MCs associated with active region eruptions are formed by magnetic reconnection between these regions and their larger-scale surroundings, rather than simple eruption or entrainment of pre-existing structures in the corona or chromosphere. We discuss our findings in the context of other recent works on both the solar and interplanetary sides, including ion composition and various MHD models of magnetic cloud formation.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The solar sources of near-relativistic $(E > $30 keV) electron events observed at 1 AU are poorly understood. In general, the solar injection times deduced from the observed 1 AU onset times and assumed 1.2 AU travel distances yield injection times about 10 minutes after the associated flare impulsive phases and type III radio burst times. One interpretation is that the apparent delays occur in the interplanetary medium, probably due to scattering of the electrons. If the injection times are delayed from the impulsive phases, the electron acceleration might take place in CME-driven shocks. Here a large number of electron events observed with the UC/Berkeley 3DP detector on the Wind spacecraft are compared with CMEs observed by the Lasco coronagraph on SOHO and with type II bursts observed by the 40 to 800 MHz radio receiver at the Astrophysikalisches Institut Potsdam (AIP) and by the 20 kHz to 14 MHz WAVES instrument on the Wind spacecraft. The acceleration of at least some of the electron events is not consistent with the shock hypothesis.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Although we are on the descending branch of solar cycle 23, a very strong active region, NOAA 652, crossed the solar visible hemisphere during the second half of July 2004. Its very large sunspot was of beta- gamma- delta type. This active region was a source of numerous X-ray flares and coronal mass ejections. Being in a favorable position not far from the equator, it represented a threat to planet Earth particularly when near its central meridian passage.

Using EIT images, it was possible to locate the position of the 2004 July 25 CME ejection as dimming of several loops to the SW of AR 652. As usual, the CME lift up was accompanied by type IV burst and followed by type II burst and a proton flare.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

In a recent study Andrews found that approximately 40% of M-class flares between 1996 and 1999, classified according to GOES X-ray flux, are not associated with Coronal Mass Ejections (CMEs). Using 133 events from his dataset for which suitable photospheric magnetograms and coronal images were available, we studied the pre-flare coronal helicity of the active regions that produced big flares. The coronal magnetic field of 78 active regions was modeled under the “constant $\alpha$” linear force-free field assumption. We find that in a statistical sense the pre-flare value of $\alpha$ and coronal helicity of the active regions producing big flares that do not have associated CMEs is smaller than the coronal helicity of those producing CME-associated big flares. A further argument supporting this conclusion is that for the active regions whose coronal magnetic field deviates from the force-free model, the change of the coronal sign of $\alpha$ within an active region is twice more likely to occur when the active region is about to produce a confined flare than a CME-associated flare. Our study indicates that the amount of the stored pre-flare coronal helicity may determine whether a big flare will be eruptive or confined.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Very large solar energetic particle (SEP) events occur at the rate of about 10 per year during solar maximum. The primary accelerators in these events are shocks driven by fast coronal mass ejections, in which speeds are greater than about 1000 km/s. Solar Cycle 23 probably produced the largest fluence of > 10 MeV/nucleon SEPs seen since the start of the Space Age. New instruments on Wind, ACE, SOHO, and other satellites have provided unprecedented detail on the energy spectra, elemental and isotopic composition, ionic charge states, and temporal evolution of these SEP events, as well as their associated CMEs and flares. In this talk, I will review some of the new insights provided by these data. A particular challenge in SEP studies has been the very large event-to-event variability in composition and spectral characteristics, particularly at energies above a few tens of MeV per nucleon. I will discuss recent efforts to understand this variability in terms of seed populations and shock geometry. I will also review recent studies of the time at which SEPs first appear on the Sun-Earth magnetic field line and the implications of these studies for the conditions under which SEP production was initiated.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A multi-channel SPIRIT telescope/spectroheliograph aboard the CORONAS-F satellite operating in soft X-ray and EUV ranges ($T \sim $0.05–15 MK) is an effective instrument for complex studies of CME-associated phenomena such as eruptive filaments, dimmings, coronal waves, posteruptive arcades, etc. In particular, SRIRIT observations of high-temperature (T = 5–15 MK) plasma structures in the MgXII 8.42 Å line show specific pre-CME sigmoid magnetic field configurations. Eruptions of filaments (prominences) and dimmings in a CME process are seen with a high contrast in the coronal 175 Å band (FeIX–XI) and the transition-region 304 Å (HeII) images. Our results are illustrated by several powerful eruptive events of the current solar cycle. We compare SPIRIT data with observations at other spaceborne and ground-based instruments (SOHO/EIT, Yohkoh/SXT, and H$\alpha$ images, etc.)To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Ground based radio imaging observations play an useful role in the study of mass ejections from the solar corona since they do not have the limitation of an occulter and both the disk/limb events can be detected early in their development, particularly via the thermal bremmstrahlung emission from the frontal loop of the CME. I present here some of the recent results on the above topic using data obtained with the Gauribidanur radioheliograph, near Bangalore in India.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Tokamak physics shows that there will be a neoclassical effect in current-carrying plasma loops. We apply the theory to solar coronal loops and hope to find a fast magnetic reconnection mechanism for understanding solar flares and CMEs.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We examine the energetics of the best examples of flux-rope CMEs observed by LASCO in 1996-2001. We find that 69% of the CMEs in our sample experience a driving power in the LASCO field of view. For these CMEs which are driven, we examine if they might be deriving most of their driving energy by coupling to the solar wind. We do not find conclusive evidence to support this hypothesis. We adopt two different methods to estimate the energy that can possibly be released by the internal magnetic fields of the CMEs. We find that the internal magnetic fields are a viable source of driving power for these CMEs.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We studied the association between SEP events during 1977-2003 and related CMEs and found each GLE event was associated with a primary CME, which was faster (average speed $\sim$1762 $km \cdot s^{-1}$) and wider (average angle width of $317^{0}$) than an average CME . All SEP-related CMEs distributed within solar source regions of latitude strip of S$30^{0}$-N$40^{0}$, while 11 (85%)GLE-related CMEs originated from the western hemisphere. These fast halo CMEs (75% full-halo and 25% partial-halo) were associated with type II radio bursts in the decameter hectometer (DH) wavelengths.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html