Coronal mass ejections (CMEs) are sources of the strongest geomagnetic disturbances. From sunspot minimum to sunspot maximum, the intensity of storms associated with CMEs increases but the degree of association decreases. We divide the CMEs in the last solar cycle (1996–2002) into magnetic clouds (MCs)and CMEs which are not magnetic clouds. MCs are much more geoeffective than non-MC CMEs, and the portion of CMEs which are MCs is maximum in sunspot minimum and minimum at sunspot maximum, corresponding to the net helicity transferred from the solar interior into the corona. The smaller portion of the more geoeffective MCs is the explanation of the smaller degree of association of CMEs with geomagnetic disturbances in sunspot maximum.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

More than 40 gradual SEPs have been observed by GOES and SOHO from 2001 to 2003. During 12 SEPs of all these events, energetic electron flux enhancements with energies from 38 keV to 337 keV were observed by RAPID onboard Cluster spacecraft. During these 12 events the variation of the energetic electron flux measured by RAPID/Cluster was closely associated to the variation of the solar energetic proton flux. The observed energetic electron flux was independent on the location of Cluster in the magnetosphere and the background level of magnetospheric electrons (even when the Cluster spacecraft was crossing the magnetopause, the plasma sheet and the low latitude boundary layer). The similar variation of the enhancement of energetic electron flux has also been observed by POLAR and Geotail in some of these events. In some of these events, the electron measurement of RAPID/Cluster will not be contaminated by the SEP protons.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We studied the relationship between successive coronal mass ejections (CMEs) and a long-lived geomagnetic storm (LLGMS) by examining the 1998 May 4 event. Five successive CMEs from the same active region and four interplanetary shocks were found to be associated with this LLGMS. We investigated the effect of successive and interacting CMEs on the LLGMS.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Several Halo CMEs hit the Earth in the second half of July 2004. They were produced by the very large complex active region NOAA 652 (Yousef et al. 2005). For CME details consult the web (ftp://lasco6.nascom.nasa.gov/pub/lasco/status/LASCO_CME_List_004).

We focus on the 26$^{th}$ -27$^{th}$ of July CME hit. This CME was associated with the long-duration M1 flare at 25/15:14. It made a very fast Sun to Earth transit-just over 31 hours (SGAS 27 July 2004). A greater than 10 MeV proton event began at 25/18:55. Solar wind speed remained elevated from 500 to over 700 km/s. A Severe Geomagnetic storm was observed and the aurora was seen as far as California.

A strong shock impacted the ACE spacecraft at 26/22:28. A sudden impulse (SI) of 96 nT was observed on the Boulder magnetometer at 22:51. The IMF Bz component was turned negative (−18 nT). Generally speaking, according to de Pater and Lissauer (2001), since a strong CME disturbance in the solar wind is usually preceded by an interplanetary shock followed by an enhanced density and velocity, the field strength first increases when the disturbance hits the magnetosphere, inducing an increase in the ring current. Several hours(up to over 25 hrs) the field strength Dst decreases dramatically during the storm main phase which typically lasts for a day The main phase is caused by an increase in the ring current, resulting from an enhanced particle flow towards the Earth. It is well known that geomagnetic storms tend to occur when IMF is directed southward. Magnetic reconnection occurs between the negative IMF and the magnetosphere thus opens the field lines with one end connected to the Earth (Dungey 1963). This magnetic reconnection allowed the protons and electrons to leak in. The proton and electron flux maximums occurred around the time of geomagnetic storm commencement which lasted for about 27 h (fig. 1). This is in agreement with the statement of Robinson (2003) that large numbers of energetic protons are constrained to occupy the region around the IP shock. The IMF Bz component dropped to −20 nT on 27 of July at 12:00 UT as measured by ACE satellite while Kp reached a maximum of 9 around 15:00 UT at the storm maximum as seen in fig. 2.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

As young stars evolve from the time of their formation onto the main sequence, they lose mass in a variety of ways. At the very earliest stages, mass loss may be in the form of jets associated with accretion from a surrounding disk. These cool jets carve out the surrounding gas and their changes over time may indicate changes in the star-formation process. At later stages, mass loss is predominantly in the form of a hot, magnetically channelled wind that carries mass, but more importantly angular momentum, away from the star. This wind determines the rotational evolution of cool stars and is intimately connected to the process of field generation deep inside the star. Mass loss also occurs in a sporadic way in the form of the ejection of cool clouds of coronal gas. The coronal distribution and evolution of these clouds (or prominences) gives us vital clues about the structure and short-timescale evolution of stellar coronae. In this review I will discuss recent advances in our understanding of the coronae, winds and accretion processes in cool stars and show how these processes may be related at different stages of evolution.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

I discuss in this contribution the accretion and ejection processes occurring in solar-type young stars. Understanding these two important processes, and their link, is one of the major issues in star formation. The magnetic field is thought to play a central role in both extracting the angular momentum from the disk and directing the accretion flow onto the star. I will focus on the well studied T Tauri stars, optically-revealed pre-main sequence stars with ages 1-10 Myrs and mass $\simeq$ 0.5 M$_{\odot}$. In the first part of this contribution, I present the current paradigm for magnetically channeled accretion, where the stellar magnetic field truncates the disk and directs the accretion flow and discuss recent observations, which indicate that this process is non-axisymmetric and time-dependent. I then turn to the study of the supersonic collimated jets observed in young stars. Magneto-hydrodynamic processes are the most likely driving mechanism. I present the main steady and non-steady outflow models, as well as constraints brought by recent high-resolution studies. I finally discuss the origin of time variability in jets.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The very active RS CVn-type star UX Ari was observed using high-resolution echelle spectrograph attached to the 2.16m telescope of Xinglong station in Nov.-Dec. 2001 and Dec. 2002. By means of synthetic spectral subtraction method, the information about chromospheric activity of the system was obtained through several chromospheric activity indicators HeI D$_3$, NaI D$_1$D$_2$, H$_{\alpha}$, and CaII IRT lines. Based on the analysis for these activity indicators, we found that the chromospheric activity of UX Ari showed obvious orbital modulation phenomenon, and the favorite active longitudes were around the quadratures of the binary system. During the two observing runs, hot plage and very strong optical flare events were detected, which were always happened around the favorite active longitudes of the system. Moreover, they were linked with the photospheric starspots in spatial structure, and appeared just above the main starspots.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The continuum energy distributions of R127 and R110 in the outburst phase are fitted by use of a optically envelope model. Both stars show two peaks in the continuum energy distributions in which one lies in the short-wavelength range (near 1250Å) and the other in the optical band. We suggest that the fluxes in the UV and optical bands may have different origins: the UV flux comes from the central star and the optical flux comes from the expanded optically envelope. We construct such a model for LBVs with the use of two LTE atmosphere models with different temperatures, and find it to be in satisfactory agreement with the observed spectral energy distributions of R127 and R110.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We investigate temporal fluctuations in the H$\alpha$ emission profiles of the RS CVn system HR 1099 from a monitoring using the MuSiCoS spectropolarimeter (Observatoire du Pic du Midi, France) in 2001, between December 01 and December 18. Part of the observed emission fluctuations is consistent with rotational modulation, which we interpret as the spectral signature of a dense and complex prominence system trapped in the magnetosphere of HR 1099 and forced to co-rotate with the binary system. The distribution of emitting material is mapped by means of Doppler tomography. We discuss the evolution of prominences over the observing window.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html