Solar activity undergoes a variation over time scales of several months known as Rieger-type periodicity, which usually occurs near maxima sunspot cycles. An early analysis showed that the periodicity appears only in some cycles, and is absent other But appearance/absence during different cycles has not been explained. We performed wavelet data from Greenwich Royal Observatory Belgium 14-24. found periods occur all but they are cycle-dependent: shorter stronger Our revealed 185-195 days weak...

Height series of Hα spectra in solar limb spicules obtained with the 53 cm coronagraph Abastumani Astrophysical Observatory are analyzed. Each height covered 8 different heights beginning at 3800 km above photosphere. The spatial difference between neighboring was 1, consequently ~3800-8700 distance photosphere has been covered. total time duration each 7 s. We found that nearly 20% measured show a periodic distribution Doppler velocities. suggest this periodicity velocity is caused by...

Here we report on the unique observation of flaring coronal loops at solar limb using high resolution imaging spectropolarimetry from Swedish 1-meter Solar Telescope. The vantage position, orientation and nature chromospheric material that filled flare allowed us to determine their magnetic field with unprecedented accuracy weak-field approximation method. Our analysis reveals strengths as 350 Gauss heights up 25 Mm above limb. These measurements are substantially higher than a number...

Aims.We analysed the consecutive height series of Hα spectra in solar limb spicules taken on 53 cm coronagraph Abastumani Astrophysical Observatory at heights 3800-8700 km above photosphere. Our aim is to observe oscillatory phenomena and consequently trace wave propagations through chromosphere.

Rieger-type periodicity has been detected in different activity indices over many solar cycles. It was recently shown that the correlates with having a shorter period during stronger Solar level is generally asymmetric between northern and southern hemispheres, which could suggest presence of similar behavior periodicity. We analyse sunspot area/number total magnetic flux data for hemispheres cycles 19-23 had remarkable north-south asymmetry. Using wavelet analysis area number...

The present paper discusses results of a statistical study the characteristics coronal hole (CH) rotation in order to find connections internal Sun. goal is measure CH rates and their distribution over latitude area sizes. In addition, are compared with solar photospheric inner layer rotational profiles. We holes observed within $\pm 60$ longitude degrees from disc centre during time span 1 January 2013 20 April 2015, which includes extended peak cycle 24.We used data created by Spatial...

Acoustic waves and pulses propagating from the solar photosphere upwards may quickly develop into shocks due to rapid decrease of atmospheric density. However, if they propagate along a magnetic flux tube, then nonlinear steepening be balanced by tube dispersion effects. This result in formation sausage soliton. The aim this letter is report an observational evidence soliton chromosphere. Time series Ca II H line obtained at limb with Solar Optical Telescope (SOT) on board Hinode analysed....

The formation and dynamics of coronal rain are currently not fully understood. Coronal is the fall cool dense blobs formed by thermal instability in solar corona towards surface with acceleration smaller than gravitational free fall. We aim to study observational evidence trace detailed individual blobs. used time series 171 \AA\, 304 spectral lines obtained Atmospheric Imaging Assembly (AIA) on board Solar Dynamic Observatory (SDO) above active region AR 11420 February 22, 2012....

A new method for the determination of open cluster membership based on a cumulative effect is proposed. In field plate relative x and y coordinate positions each star with respect to all other stars are added. The procedure carried out two epochs t_1 t_2 separately, then one sum subtracted from another. For differences in its will be accumulated. star, contrary, changes members at very small. On histogram sums gather left diagram, while form tail right. allows us efficiently discriminate...

We study the detailed dynamics of a solar prominence tornado using time series 171, 304, 193 and 211 {\AA} spectral lines obtained by Solar Dynamics Observatory/ Atmospheric Imaging Assembly during 2012 November 7-8. The first appeared at 08:00 UT, 07, near surface, gradually rose upwards with mean speed $\sim$ 1.5 km s$^{-1}$ persisted over 30 hr. Time-distance plots show two patterns quasi-periodic transverse displacements axis periods 40 50 minute different phases evolution. pattern...

A set of 23 observations coronal jet events that occurred in bright points has been analyzed. The focus was on the temporal evolution mean brightness before and during events. In absolute majority cases either single or recurrent jets were preceded by slight precursor disturbances observed intensity curves. key conclusion is we able to detect quasi-periodical oscillations with characteristic periods from sub-minute up 3-4 min values point which precede jets. Our basic claim along...

Context. Total solar irradiance allows for the use of Sun as a star studying observations stellar light curves from recent space missions. Aims. We aim to study how mid-range periodicity observed in activity indices influences total irradiance. Methods. studied periodic variations based on SATIRE-S and SOHO/VIRGO data during cycles 23-24 timescales Rieger-type periodicity. Then we compared power spectrum oscillations those sunspot faculae determine their contributions. Results. Wavelet...

Context. A Rieger-type periodicity of 150–180 days (six to seven times the solar rotation period) has been observed in Sun’s magnetic activity and is probably connected with internal dynamo layer. Observations Rieger cycles other solar-like stars may give us information about action throughout stellar evolution. Aims. We aim use Sun as a star analogue find on using Kepler data. Methods. analyse light curve Sun-like KIC 2852336 (with period 9.5 days) wavelet generalised Lomb-Scargle methods...

Rossby waves arise due to the conservation of total vorticity in rotating fluids and may govern large-scale dynamics stellar interiors. Recent space missions collected huge information about light curves activity many stars, which triggered observations surface We aim study theoretical properties stratified interiors uniformly radiative stars with sub-adiabatic vertical temperature gradient. use equatorial beta-plane approximation linear gradient equatorially trapped inertia-gravity stars....

Active regions (ARs) are the main sources of variety in solar dynamic events. Automated detection and identification tools need to be developed for features a deeper understanding cycle. Of particular interest here dynamical properties ARs, regardless their internal structure sunspot distribution. We studied oscillatory dynamics two ARs: NOAA 11327 11726 using different methods pattern recognition. novel method automated AR border compared it an existing proof-of-concept. The first uses...

Abstract. Javakheti Highland is one of the most seismic active regions Caucasus. The majority earthquakes observed throughout region occur within this small area (f = 40.8° – 41.8° ; l 43.3° 44.3°). One can expect that exclusive activity testifies to global geophysical processes which take place Caucasus region. Based on above-mentioned, interest was study variation with time number occurring in We analysed some 695 relatively (2.5 < M 6.0) Javalkheti period 1961–1992 regard large >...

We studied the dynamics of all prominence tornadoes detected by Solar Dynamics Observatory/Atmospheric Imaging Assembly from 2011 January 01 to December 31. In total, 361 events were identified during whole year, but only 166 traced until end their lifetime. Out tornadoes, 80 (48%) triggered CMEs in hosting prominences, 83 (50%) caused failed coronal mass ejections (CMEs) or strong internal motion and 3 (2%) finished lifetimes without any observed activity. Therefore, almost lead...

The present paper deals with an attempt to check up the theoretical model of self-generated seismo-electromagnetic oscillations LAI system on basis retrospective data. Application offered simple enables one explain qualitatively mechanism VLF electromagnetic emission initiated in process earthquake preparation. It is worth pay attention fact that frequency changes from MHz kHz spectrum comes a good agreement avalanche-like unstable fault formation. L'Aquila taken as example isolate reliably...

Abstract. It is acceptable that earthquakes certain exogenous (cosmic) triggering factors may exist in every seismoactive (s/a) region and Caucasus among them. They have to correct earthquake occurring moment or play the role case when at limit of critical value geological medium course. Our aim reveal some possible initiate earthquakes, on example s/a region, taking into account very complex by point view tectonic stress distribution. The compression directed from North South (and vice...

Context. The dynamics of the flaring loops in active region (AR) 11429 are studied. observed consist several evolution stages loop system during both ascending and descending phases registered M-class flare. dynamical properties can also be classified by different types magnetic reconnection, related plasma ejection aperiodic flows, quasi-periodic oscillatory motions, rapid temperature density changes, among others. focus present paper is on a specific time interval (pre-flare) phase. Aims....