The purpose of this paper is to analyze the multi-wavelength and multi-instrument observations of two quiescent filament eruptions as well as the deflection of associated CMEs from the radial direction. The events occurred on 18 October 2017 and 9 May 2021, respectively, in the southern solar hemisphere. Both of them and associated flares were registered by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO) and the Solar Terrestrial Relations Observatory–Ahead (STEREO A) Observatory in different EUV wavebands. Using data from STEREO A COR1 and COR2 instruments and the Large Angle and Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO), we investigated morphology and kinematics of the eruptions and the latitudinal offset of the related CMEs with respect to the erupting filaments. Our observations provide the evidence that the two filament eruptions were highly non-radial. The observed deviations are attributed to the presence of low-latitude coronal holes.

We present the results from the investigation of a filament eruption (FE), occurring in the southern solar hemisphere on 2017 Oct 18. The event was observed in the field-of-view (FOV) of Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) and was associated with a halo CME. The CME displayed a strong non-radial motion towards the pole. The source region of the eruption was located behind the limb and was well observed in STEREO A FOV, as a circular filament, close to the disk center. We analyzed the filament eruption kinematic, using the two observable point of view. The CME latitudinal offset with respect to the erupting filament in LASCO field-of-view was investigated, as well. The possible reason for CME deflection is discussed.

We present the results from the investigation of a filament eruption, occurring in the southern solar hemisphere on October 18, 2017. The event was observed in the field- of-view of Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) and STEREO A observatory and was associated with a halo CME. The CME displayed a strong non-radial motion towards the pole. The eruption started behind the limb, from a circular filament, close to the disk center.We studied the eruption kinematic, using data from EUVI STEREO A. Additionally, the latitudinal offset of the CME with respect to the erupting filament in the LASCO field- of-view was examined.

We present the observations of a quiescent filament eruption and its deflection from the radial direction. The event occurred in the southern solar hemisphere on 2021 May 9 and was observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO), by the STEREO A Observatory and GONG. Part of the filament erupted in the west direction, while major part of the filament deviated towards east direction. LASCO observed a very weak CME towards the west direction where it faded quickly. Moreover, the eruption was associated with CME observed by STEREO A COR1 and COR2. Our observations provide the evidence that the filament eruption was highly non-radial in nature.

We present the observations of three sympathetic filament eruptions occurring on 19 July 2015 namely F1, F2, and F3. The events were observed in UV/EUV wavelengths by Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory and by Global Oscillation Network Group telescope in Hα line. As filament F1 starts to erupt, a part of it falls close to the location of the F2 and F3 filaments. This causes the eruption of F2 and F3 during which the two filaments merge together and trigger a medium-class CME and a longduration GOES C2.1 class flare. We discuss the dynamics and kinematics of these three filament eruptions and related phenomena.

Prominence eruptions (PEs) are one of the fundamental precursors of coronal mass ejections (CMEs). Moreover, PEs play a crucial role in triggering CMEs. Therefore, understanding the initiation and evolution of the erupting prominences provides a crucial physical understanding of the CME initiation and evolution, as well its broader impacts on space weather and geospace climate. This review focuses on the PEs and their associated CMEs in five events. Three events represent an eruption of a single prominence/filament flux rope(FR). The other events present interaction and eruption of two nearby FRs of the same prominence. The five events differ from one another by the type, pre-eruption and eruption evolution of PEs and specific properties of the linked CMEs. The magnetic properties of the source region and overlying magnetic arcade as main factors for the specific physical linkage between PE and CME are discussed for the five events.

We report a detailed study of the relationship between solar filament eruption, flare productivity and CME kinematics relevant to Solar Energetic Particle (SEP) events. We analyze kinematics and morphological behaviors of 32 filament eruptions appearing during the Solar Cycle 24, between Aug 14, 2010 and April 18, 2016. For our analysis a high resolution data in different Extreme Ultraviolet (EUV) channels from Solar Dynamic Observatory (SDO) are used. Each of the observed eruptions is associated with solar flare and is followed by in situ observed proton events. The kinematics properties of the associated CME are tracked. We perform a statistical chronological study of the observed sequence of events in order to reveal the eruption triggers and the evolved physical mechanisms.

We study the precursor phase, activation, and ejection of solar surge occuring on 2014 March 14. The surge was associated with an eruptive prominence (EP), several flares and partial-halo coronal mass ejection (CME). For our study we used EUV data from the Atmospheric Imaging Assembly on board of the Solar Dynamics Observatory. The surge occurred in an young active region in a flux emergence phase located beneath a multiple-arcade helmet streamer. The surge appeared at the footpoints of the EP massive flux rope (MFR) as a flare-like loop. The surge upward motion clearly showed two subphases: acceleration and deceleration ones. During the first subphase, the surge rose up to height of 45 Mm with growing speed in the range 3-65 km/s and accelerations from 0.5 m/s(2) to 129 m/s(2). During the second subphase, the surge began to rise with constant deceleration of -54.8 m/s(2) and a decreasing speed from 60 to 3 km/s. During the surge downward motion the plasma fell back with a speed of 27 km/s. The surge ejection revealed four episodes in its EUV brightening evolution. During the surge downflow phase, the EUV brightening enhancement at the footpoints of surge-EP system suggests surge mass impact at this place, which plays a key role in bright flux rope (BFR) initiation and formation underneath the slowly rising EP MFR. Taking into account the crucial role of the BFR for further EP evolution, we conclude that the EP was triggered by the surge via tether-cutting reconnection.

In this work we present a comparative analysis of two filament/prominence eruptions (EP) driven by helical kink instability. First EP on 2010 March 30 presented a kink induced confined eruption of a single magnetic flux rope (FR) followed of partial FR reformation, which was associated with coronal mass ejection (CME). The second EP on 2014 May 4 represented kink induced eruptions of two coupled FRs of the same filament that were interacting and splitting during the eruption. The first FR underwent a confined eruption followed of FR reformation while the second FR underwent a successive partial eruption, which was associated with CME. The physical processes in the EPs environments, such as magnetic emergence, cancellation or shearing, reconnection signatures, overlaying magnetic arcades and the activity events accompanying the eruptions were analyzed. This work laid special emphasis on specific conditions, which are crucial for the type of the filament eruptions and their kinematics and evolution.

We present a comparison study of two filament/prominence eruptions driven by helical kink instability. First one, eruptive prominence (EP) on 2010 March 30, is a single magnetic flux rope (FR) that undergoes confined kink induced eruption. The second EP on 2014 May 4 represents kink induced eruptions of two threads of the same filament: the first FR undergoes a confined eruption while the other FR - a full eruption. The physical processes in the EPs environments, such as magnetic emergence, cancellation or shearing, reconnection signatures, overlaying magnetic arcades and the activity events accompanying the eruptions were analyzed. This study laid special emphasis on specific conditions, which are crucial for the type of the filament eruption and its kinematics.

We present very rarely reported case of an eruptive prominence (EP) composed by both hot, bright flux rope (BFR) and cool massive flux ropes (MFR) and associated partial-halo coronal mass ejection (CME). Using SDO and STEREO A and B multi-wavelength observations, we examined in detail the eruption of EP flux ropes (FRs) and their associated activities in a complex magnetic configuration located beneath a multiarcade helmet streamer. We establish the sequence of activities appearance involved in casually linked chain of events on 2014 March 14: short-lived active region, surge eruption, EP BFR rising, EP BFR and MFR merging and interacting, EP common FR fast rise, flare, EP FR bifurcation, partial-halo CME with bi-component bright core, impulsive flare, post-flare loop arcade. A surge-like event in the northern EP footpoints is determined as the possible trigger of the bright FR appearance beneath the cool, massive FR. Plasma draining in this footpoints is identified as the precursor for the EP eruption. We find that the EP FRs merging at the fast-rise onset and their splitting in the phase of strong acceleration are the main triggers for the flaring activity. Studying the eruptions of EP hot and cool FRs with their associated CME, we find that they are co-spatial with the CME bright core, i.e. the hot and cool EP FRs produced bi-component CME bright core.

. We report the first results from the study of an asymmetric eruptive prominence (EP) that appeared on 01 Nov 2014 and was followed by a two-ribbon solar flare. The ejection triggered a fast coronal mass ejection (CME) that was well visible in the LASCO C2 field of view. The morphology and kinematics of the EP and two-ribbon flare were examined by multi-channel observations from AIA/SDO and SoHO/LASCO. Initially, the EP slowly rose and then it sharply ejected up with a strong acceleration producing the CME bright core. The evolution of two-ribbon flare is morphologically characterized by separation of the two ribbons in the chromosphere. The ribbons' separation showed two-stage evolution: first one with relatively fast decelerating motion and very slow second one with low constant velocity. Such separating motion is believed to provide a signature of the reconnection process occurring progressively higher up in the corona.

Coronal mass ejections (CMEs), one of the most energetic manifestations of solar activity, are complex events, which combine multiple related phenomena occurring on the solar surface, in the extended solar atmosphere (corona), as well as in interplanetary space. We present here an outline of a new collaborative project between scientists from the Bulgarian Academy of Sciences (BAS), Bulgaria and the University of Graz, Austria. The goal of the this research project is to answer the following questions: 1) What are the properties of erupting filaments, CMEs, and CME-driven shock waves near the Sun, and of associated solar energetic particle (SEP) fluxes in interplanetary space? 2) How are these properties related to the coronal acceleration of SEPs? To achieve the scientific goals of this project, we will use remote solar observations with high spatial and temporal resolution to characterize the early stages of coronal eruption events in a systematic way – studying the preeruptive behavior of filaments and flares during energy build-up, the kinematics and morphology of CMEs and compressive shock waves, and the signatures of high energy non-thermal particles in both remote and in situ observations. ПРЕДСТАВЯНЕ НА ПРОЕКТ “ИЗСЛЕДВАНЕ НА РАННИТЕ СТАДИИ НА СЛЪНЧЕВИТЕ ИЗРИГВАНИЯ – ОТ ДИСТАНЦИОННИ НАБЛЮДЕНИЯ КЪМ ВИСОКОЕНЕРГЕТИЧНИ ЧАСТИЦИ” Камен Козарев, Астрид Верониг, Петър Духлев, Костадинка Колева, Момчил Дечев, Росица Митева, Мануела Темер, Карин Дисауер Институт по Астрономия с НАО – Българска академия на науките Институт по физика, Университет „Карл-Франц“, Грац, Австрия Институт за космически изследвания и технологии – Българска академия на науките e-mail: kkozarev@astro.bas.bg Ключови думи: Коронални изхвърляния на маса, слънчеви високоенергетични частици, коронални ударни вълни, еруптивни влакна Резюме: Короналните изхвърляния на маса (Coronal Mass Ejections – CME), едно от найенергетичните проявления на слънчевата активност, са комплексни събития, съпътствани от множество свързани феномени върху слънчевата повърхност, в слънчевата атмосфера (короната), както и в междупланетното пространство. Тук представяме нов съвместен проект между учени от Българската академия на науките (БАН), България, и Университет “Карл-Франц”, Грац, Австрия. Целта на представения проект е да отговори на следните въпроси: 1) Какви са свойствата на еруптивните протуберанси, короналните изхвърляния на маса и ударните вълни предизвикани от тях в близост до слънцето (в слънчевата корона), както и на произтичащите от тях потоци високоенергетични частици в междупланетното пространство? 2) Как са свързани тези свойства с ускорението на слънчеви високоенергетични частици в короната? За да изпълним научните цели на този проект, ще използваме дистанционни слънчеви наблюдения с висока времева и пространствена разделителна способност, за да изследваме най-ранните етапи на слънчевите изригвания по систематичен начин – като проучим пред-еруптивното поведение на протуберанси и избухвания в

In this work, we report results from the study of a filament/prominence eruption on 2014 May 4. This eruption belongs to the class of rarely reported causally linked eruptions of two coupled flux tubes (FTs) of a quiet region filament. We made a comparative analysis based on multiwave observations from Solar Dynamics Observatory (SDO) and Solar Terrestrial Relations Observatory (STEREO) A and B combining the high temporal and spatial data taken from three different viewpoints. The main results of the study are as follows: (1) The source of the eruptive prominence consists of two coupled FTs located near the eastern limb: top-located one (FT1) and bottom-located one (FT2). (2) FT1 and FT2 had the same helicity, i.e. left-handed twist and writhe. Their untwisting motion during eruption suggests that kink instability seems to act. (3) The kinematic evolution of the FT1 suggests a slow successful eruption that was associated with a slow CME. (4) The FT2 exhibited failed kinked eruption with a non-radial propagation followed by its reformation. This eruption was accompanied of apparent mass draining in the legs, flare-ribbons and post-flare EUV arcade. (C) 2017 Elsevier B.V. All rights reserved.

The results from the study of daily average values of the background concentrations of nitrogen oxides (NO and NO2) in the terrestrial atmosphere are presented. The study aim was to reveal some aspects of the relation between the solar flares, as sources of solar energetic protons (SEP-Solar Energetic Protons), and the nitrogen oxides formation in the Earth's atmosphere. For this aim, except the time series of the nitrogen oxides for the period Oct 15, 2004 Sept 1, 2009, the total daily fluxes of the solar protons for the energy diapasons E >= 10 M eV and E >= 100 M eV , registered by GOES-11 and GOES-13 satellites, were used. The obtained results suggest that the significant peaks in the time series of the nitrogen oxides should be explained with 'volley' effect of NO and NO2 formations in the middle atmosphere. Such formation processes take place in the time interval from one month to about one year before the peaks registration at the ground-level station of the Rozhen National Astronomical Observatory. In view of the short period with continuous time series, to give a certain answer of the question whether and how the solar protons affect the NO and NO2 formation it is necessary to prolong the study in future.

The subject of this paper is the existence and stability of solar cycles with durations in the range of 20-250 years. Five types of data series are used: 1) The Zurich series (1749-2009 AD), the mean annual International sunspot number Ri, 2) The Group sunspot number series Rh (1610-1995 AD), 3) The simulated extended sunspot Rsi number from Extended time series of Solar Activity Indices (ESAI) (1090-2002 AD), 4) The simulated extended geomagnetic aa-index from ESAI (1099-2002 AD), 5) The Meudon filament series (1919-1991 AD) (it is used only particularly). Data series are smoothed over 11 years and supercenturial trends are removed. Two principally independent methods of time series analysis are used: the T-R periodogram analysis (both in the standard and "scanning window" regimes) and the wavelet-analysis. The obtained results are very similar. It is found that in all series a strong cycle with mean duration of 55-60 years exists. It is very well expressed in the 18th and the 19th centuries. It is less pronounced during the end of the 19th and the beginning of the 20th centuries. On the other hand a strong and stable quasi 110-120 years and ~200-year cycles are obtained in all of these series except in Ri. In the last series a strong mean oscillation of ~ 95 years is found, which is absent in the other data sets. The analysis of the ESAI (1090-2002 AD) proved that the quasi century cycle has a relatively stable doublet (~80 and ~120 years) or triplet (~55-60, 80 and 120 years) structure during the last ~900 years. An interesting feature in all series is the existence of significant ~29-year cycle after the last centurial Gleissberg-Gnevishev's minimum (1898-1923 AD). Most probably the different types of oscillations in the sub-century and century period range correspond to cycles of different classes of active regions.

The present study provides important details on homologous eruptions of a solar prominence that occurred in active region NOAA 10904 on 2006 August 22. We report on the pre-eruptive phase of the homologous feature as well as the kinematics and the morphology of a forth from a series of prominence eruptions that is critical in defining the nature of the previous consecutive eruptions. The evolution of the overlying coronal field during homologous eruptions is discussed and a new observational criterion for homologous eruptions is provided. We find a distinctive sequence of three activation periods each of them containing pre-eruptive precursors such as a brightening and enlarging of the prominence body followed by small surge-like ejections from its southern end observed in the radio 17 GHz. We analyse a fourth eruption that clearly indicates a full reformation of the prominence after the third eruption. The fourth eruption although occurring 11 h later has an identical morphology, the same angle of propagation with respect to the radial direction, as well as similar kinematic evolution as the previous three eruptions. We find an important feature of the homologous eruptive prominence sequence that is the maximum height increase of each consecutive eruption. The present analysis establishes that all four eruptions observed in Ha are of confined type with the third eruption undergoing a thermal disappearance during its eruptive phase. We suggest that the observation of the same direction of the magnetic flux rope (MFR) ejections can be consider as an additional observational criterion for MFR homology. This observational indication for homologous eruptions is important, especially in the case of events of typical or poorly distinguishable morphology of eruptive solar phenomena. (C) 2016 Elsevier B.V. All rights reserved.