The relationship between the speed of coronal mass ejections and the peak soft X-ray flux of the associated flares is studied for events occurring near the solar limbs between 1996 and 2008. An improved, though still moderate, correlation between the two parameters is found.

We investigate the violent events in the cluster of two active regions (ARs), NOAA numbers 11121 and 11123, observed on 11 November 2010 by the Solar Dynamics Observatory (SDO). Within one day the magnetic field intensity increased by 70% with the emergence of new groups of bipoles in AR 11123, where three filaments are seen along the complex inversion line. The destabilization of the filaments led to flares and CMEs. The CMEs around 08:24 UT and 17:00 UT are directly related to the partial eruption of one filament in the new AR, as shown by a topology computation and analysis. The other CMEs on this day are due to either other ARs or to the destabilization of the global magnetic configuration of the two ARs. This conclusion can be only reached by using the three eyes of SOHO, STEREO and SDO.

On 5 January 2005, SoHO/LASCO observed two CMEs associated with eruptive filaments with different initial velocities and acceleration. The second CME accelerates much faster than the previous and the resulting interaction has been revealed in in-situ spacecraft measurements by the presence of magnetic holes at the border of the two distinct magnetic clouds. At their interface region, these magnetic clouds have embedded filament plasma that shows complex magnetic structures with a distinct magnetic flux rope configuration; these have been modeled by the Grad - Shafranov reconstruction technique. The geomagnetic consequences of these structures have been associated with substorms in recovery phase of a storm and detailed analysis is presented in Sharma et al. (2013). In the present paper, we highlight the comparison of shape and extent of two filament plasma remnants in magnetic clouds as revealed by three - dimensional (3D) reconstruction and analysis from the Solar Mass Ejection Imager (SMEI) data. The results provide an overview of the two eruptive filaments on 5 January 2005 and their interplanetary propagation.

We studied three interplanetary coronal mass ejections associated with solar eruptive filaments. Filament plasma remnants embedded in these structures were identified using plasma, magnetic and compositional signatures. These features when impacted the Earth's terrestrial magnetosphere - ionosphere system, resulted in geomagnetic storms. During the main phase of associated storms, along with high density plasma structures, polarity reversals in the Y-component (dawn-to-dusk) of the interplanetary electric field seem to trigger major auroral substorms with concomitant changes in the polar ionospheric electric field. Here, we examine the cases where plasma dynamics and magnetic structuring in the presence of the prompt penetration of the electric field into the equatorial ionosphere affected the space weather while highlighting the complex geomagnetic storm-substorm relationship.

We report observations of a long filament that underwent recurrent partial eruptions on August 4, 6, and 8, 2012. The filament reappeared in the subsequent rotation of the Sun, and disappeared completely on August 31, 2012. We implemented an automated filament detection algorithm developed by us for estimating different attributes of these filaments few hours prior to its disappearance in Hα and studied their evolution. Based on these attributes, we determine the onset time of the disappearance of Hα filaments. We then compared these onset times with that of the associated CMEs observed by LASCO/SOHO coronagraphs. This is also useful to understand temporal relationship of EUV and X-ray flux variation associated with filament disappearances in Hα. Our results show the importance of such studies in understanding the mechanism of CME initiation, particularly the role of eruptive filaments, in this process.

We study the different evolutional stages of a large quiescent prominence, mainly considering its dynamic/thermal instabilities occurred close from the boundary of coronal hole (CH). We identify the critical conditions, such as the minimum distance between the CH's boundary and prominence channel and the emergence of a new magnetic flux linked to the prominence instability and its general evolution in connection to CH. Our observations indicate peculiar filament activations prior to its thermal/dynamic instabilities, suggesting the connection of nearby CH with the general evolution of prominence and vice versa. Additionally, we analyze each evolutional stage of prominence and the associated Coronal Mass Ejections (CMEs).

Coronal mass ejections (CME) and associated interplanetary-propagated solar wind disturbances are the established causes of the geomagnetic storms which, in turn, create the most hazardous impacts on power grids. These impacts are due to the large geomagnetically induced currents (GIC) associated with variations of geomagnetic field during storms, which, flowing through the transformer windings, cause extra magnetisation. That can lead to transformer saturation and, in extreme cases, can result in power blackouts. Thus, it is of practical importance to study the solar causes of the large space weather events. This paper presents the example of the space weather chain for the event of 5-6 November 2001 and a table providing complete overview of the largest solar events during solar cycle 23 with their subsequent effects on interplanetary medium and on the ground. This compact overview can be used as guidance for investigations of the solar causes and their predictions, which has a practical importance in everyday life.

During an unusually massive filament eruption on 7 June 2011, SDO/AIA imaged for the first time significant EUV emission around a magnetic reconnection region in the solar corona. The reconnection occurred between magnetic fields of the laterally expanding CME and a neighbouring active region. A pre-existing quasi-separatrix layer was activated in the process. This scenario is supported by data-constrained numerical simulations of the eruption. Observations show that dense cool filament plasma was re-directed and heated in situ, producing coronal-temperature emission around the reconnection region. These results provide the first direct observational evidence, supported by MHD simulations and magnetic modelling, that a large-scale re-configuration of the coronal magnetic field takes place during solar eruptions via the process of magnetic reconnection.

By using the data of Solar Dynamics Observatory (SDO), we present a case study of the contraction of the overlying coronal loop and the rotation motion of a sigmoid filament on 2012 May 22. At the beginning of the filament eruption, the overlying coronal loop experienced a significant contraction. In the following, the filament started to rotate counterclockwise. We also carried the simulation to investigate the process of the filament eruption.

High-resolution spectral observations of young stars with dense protoplanetary discs like Beta Pictoris led to the discovery of variable emission lines of metal atoms, Na, Fe etc., that indicate the presence of fluxes of comet-like evaporating bodies falling onto the stars, FEBs. Assuming the presence of stellar atmospheres similar to the solar one, we show that passages of the FEBs through the stellar chromosphere and photosphere with velocities around 600 km/s will be accompanied by aerodynamic crushing of the nuclei, transverse expansion of the crushed matter, “explosion” of the flattened nuclei in a relatively very thin sub-photosphere layer due to sharp deceleration, and impulse production of a hot plasma. The impulsive rise of the layer's temperature and density lead to the generation of a strong “blast” shock wave and shock wave-induced ejection/eruption of hot plasma into space above the chromosphere. Observations of such impact-induced high-temperature phenomena are of interest for the physics/prognosis of stellar/solar flares as well as physics of comets.

The behavior of filaments and prominences during the Solar Cycle is a signature of Sun's activity. It is therefore important to follow their evolution during the cycle, in order to be able to associate it with the various phases of the Solar Cycle as well as with other Solar features or events. The virtual observatory HELIO provides information that can be used for such studies, especially its Heliophysics Feature Catalogue gives a unique access to the description of various features during around one cycle. Features available are: filaments, prominences, photospheric and coronal active regions, coronal radio emission, type III radio bursts, coronal holes and sunspots. Web interfaces allow the user to query data for these features. Useful information can also be shared with other HELIO services, such as Heliophysics Event Catalogue, which provides access to dozens of tables of events such as flares, CMEs, . . .

We have been operating an infrared Stokes spectro-polarimeter, whose observing wavelength bands include the He i 10830 Å and Fe i 15648 Å lines. A couple of full-Sun, full-Stokes maps in both wavelength bands are taken on a daily basis, with the polarization sensitivity better than 10−3. With this sensitivity, the helium polarization maps clearly show the atomic and Hanlé polarizations besides the Zeeman polarization, particularly in prominences/filaments. On these polarization maps, we can track the magnetic field signals of the prominences/filaments during their passages on the solar disk. Therefore, this instrument works as a ‘synoptic prominence magnetograph’. Our preliminary study of the linear polarizations seen in quiescent filaments suggests that the magnetic field producing the polarization signals is located at the bottom part of a flux-rope, which supports a filament.

Filaments may be mistaken for coronal holes when observed in extreme ultraviolet (EUV) images; however, a closer and more careful look reveals that their photometric properties are different. The combination of EUV images with photospheric magnetograms shows some characteristic differences between filaments and coronal holes. We have performed analyses with 7 different SDO/AIA wavelengths (94, 131, 171, 211, 193, 304, 335 Å) and SDO/HMI magnetograms obtained in September 2011 and March 2012 to study coronal holes and filaments from the photometric, magnetic, and also geometric point of view, since projection effects play an important role on the aforementioned traits.

Kanzelhöhe Observatory (kso.ac.at) performs regular high-cadence full-disk observations of the solar chromosphere in the Hα and CaIIK spectral lines as well as the solar photosphere in white-light. In the frame of ESA's Space Situational Awareness (SSA) activities, a new system for near real-time Hα image provision through the SSA Space Weather (SWE) portal (swe.ssa.esa.int) and for automatic alerting of flares and erupting filaments is under development. Image segmentation algorithms, based on optical flow image registration, for the automatic detection of solar filaments in real time Hα images have been developed and implemented at the Kanzelhöhe observing system. We present first results of this system with respect to the automatic recognition and segmentation of filaments and filament eruptions on the Sun.

Coronal Multi-channel Polarimeter (CoMP-S), developed by HAO/NCAR, has been introduced to regular operation at the Lomnicky Peak Observatory (High Tatras in northern Slovakia, 2633 m a.s.l.) of the Astronomical Institute of Slovak Academy of Sciences. We present here the technical parameters of the current version of the instrument and its potential for observations of prominences in the visual and near-IR spectral regions. The first results derived from observations of prominences in the Hα emission line taken during a coordinated observing campaign of several instruments in October 2012 are shown here.

We investigate the advantages of imaging solar filaments and prominences in Lyman-Alpha, coupled to H-Alpha on ground, to develop more reliable precursors indicators for large flares, several hours before their occurrence.

We present a summary of the scientific objectives, payload and mission profile of the Space Weather & Ultraviolet Solar Variability Microsatellite Mission (SWUSV) proposed to CNES and ESA (small mission).