A5002729726- Fluid Dynamics and Turbulent Flows
- Solar and Space Plasma Dynamics
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Geomagnetism and Paleomagnetism Studies
- Astrophysics and Star Formation Studies
- Ionosphere and magnetosphere dynamics
- Radio Astronomy Observations and Technology
- Fluid Dynamics and Vibration Analysis
- Astro and Planetary Science
- Meteorological Phenomena and Simulations
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- Phase Equilibria and Thermodynamics
- Dark Matter and Cosmic Phenomena
- Gyrotron and Vacuum Electronics Research
- Plant Water Relations and Carbon Dynamics
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Galaxies: Formation, Evolution, Phenomena
- Heat Transfer Mechanisms
- Methane Hydrates and Related Phenomena
- Adaptive optics and wavefront sensing
- Neutrino Physics Research
Abastumani Astrophysical Observatory
1997-2023
Ilia State University
2010-2016
Tbilisi State University
2014-2016
M. Nodia Institute of Geophysics
2010
Special Astrophysical Observatory
1988-1991
Variability is one of the most observable characteristics active galactic nuclei, and it important when considering emission mechanism. In this paper, we report optical photometry monitoring two nearby brightest quasars, PHL 1811 3C 273, using ST-6 camera attached to Newtonian focus Ap6E CCD primary 70 cm meniscus telescope at Abastumani Observatory, Georgia. was monitored during period from 2002 September 2012 December, while 273 1998 February 2008 May. During our period, sources did not...
We present recent optical photometric observations of the blazar OJ 287 taken during September 2015 -- May 2016. Our intense started in November and continued until 2016 included detection large outburst December that was predicted using binary black hole model for 287. For our observing campaign, we used a total 9 ground based telescopes which one is Japan, India, three are Bulgaria, Serbia, Georgia, two USA. These were carried out 102 nights with ~ 1000 image frames BVRI bands, though...
Here we report on the results of WEBT photo-polarimetric campaign targeting blazar S5~0716+71, organized in March 2014 to monitor source simultaneously BVRI and near IR filters. The resulted an unprecedented dataset spanning $\sim 110$\,h nearly continuous, multi-band observations, including two sets densely sampled polarimetric data mainly R filter. During campaign, displayed pronounced variability with peak-to-peak variations about $30\%$ "bluer-when-brighter" spectral evolution,...
This is a sequel to Paper I (Chagelishvili et al. 2003), where we presented the so-called bypass concept for onset of turbulence in shearing flows. According this concept, which was worked out during last decade by hydrodynamic community spectrally stable flows, vortical perturbations undergo transient growth extracting energy from shear (a linear process), thereby reaching an amplitude sufficient allow non-linear interactions which, positive feedback, sustain turbulence. In described 2D...
Evolution of three-dimensional magnetohydrodynamic (MHD) waves [fast magnetosonic (FMW), slow (SMW) and Alfvén waves] is studied in unbounded parallel flows with uniform shear velocity magnetic field directed along the flow. The energy exchange between MHD background flow explored. This process noticeably different for each type wave characterized by unusual (algebraic) behavior linear amplification processes. Another novelty shown evolution — coupling their mutual transformations are...
We present the results of photometric observations three TeV blazars, 3C 66A, S4 0954+658, and BL Lacertae (BL Lac), during period 2013–2017. Our extensive were performed in a total 360 nights which produced ∼6820 image frames BVRI bands. study flux spectral variability these blazars on lengthy time-scales. also examine optical energy distributions are crucial understanding emission mechanism long-term blazars. All exhibited strong our observations. The colour variations mildly chromatic...
Evolution of slow magnetoacoustic perturbations is used to demonstrate a new mechanism plane Couette flow shear energy transformation. The initial uniform magnetic field considered be directed along the unperturbed velocity. We find that amplification waves nonordinary---it occurs in limited time interval and anomalously strong. unusual behavior manifested also by fact characteristic length scale perturbation diminishes down dissipative scales not only due nonlinear cascade processes, but...
Abstract The linear dynamics of symmetric and nonsymmetric perturbations in unbounded zonal inviscid flows with a constant vertical shear velocity, when fluid is incompressible density stably stratified along the meridional directions, investigated. A small–Richardson number Ri ≲ 1 large–Rossby Ro ≳ regime considered, which satisfies condition for instability. Specific features this are closely related to nonnormality operators well interpreted framework nonmodal approach by tracing spatial...
Abstract We report on a recent multiband optical photometric and polarimetric observational campaign of the blazar OJ 287 that was carried out during 2016 September–2017 December. employed nine telescopes in Bulgaria, China, Georgia, Japan, Serbia, Spain, United States. collected over 1800 image frames BVRI bands 100 measurements ∼175 nights. In 11 nights with many quasi-simultaneous ( V , R I ) observations, we did not detect any genuine intraday variability flux or color. On longer...
Abstract The present investigation is devoted to the revealing of physical essence action rigid boundary on linear dynamics perturbations in plane shear flows. A new mathematical approach proposed which accurately and completely replaces horizontal by actions certain localized sources placed ( z = 0) original/canonical flow dynamical equations for wave vortex mode , i.e. with zero nonzero potential vorticity. elaborated example well-known problem geophysical hydrodynamics—the semi-infinite...
Abstract. Here are presented the results of experimental and theoretical studies on a stability zonal geostrophic flows in rotating layer shallow water. In experiments, special apparatus by Abastumani Astrophysical Observatory Georgian Academy Science was used. This represents paraboloid rotation, which can be set regulable rotation around vertical axis. Maximal diameter is 1.2 m, radius curvature pole 0.698 m. paraboloid, water spreads walls as uniform height under period 1.677 s. Against...
Our goal is to gain new insights into the physics of wave overreflection phenomenon in MHD nonuniform/shear flows changing existing trend/approach study. The performed analysis allows separate from each other different physical processes, grasp their interplay and, by this way, construct basic incompressible with linear shear mean velocity, ${\bf U}_0=(Sy,0,0)$, that contain two types Alfv${\rm \acute{e}}$n waves. These waves are reduced pseudo- and shear-Alfv${\rm when wavenumber along...
In this work, we present optical R band observations of AO 0235+164 carried out during the period November 2006 to December 2012 using Ap6E CCD camera attached primary focus 70 cm meniscus telescope at Abastumani Observatory, Georgia. It shows a large variation Δ = 4.88 mag (14.19–19.07 mag) and short time scale T v 73.5 min our monitoring period. When periodicity analysis methods are applied R-band data from both historic observations, periods P 1 8.26 yr 2 0.54 found.
Our goal is to gain new insight into the physics of wave dynamics in ionospheric zonal shear flows. We study flow non-normality induced linear coupling planetary scale (slow) modified Rossby waves and westward propagating fast magnetized (Khantadze) using an approach different from existing one dynamics. The performed analysis allows us separate each other physical processes, grasp their interplay, and, by this way, construct basic slow with mean velocity, U0=(Sy,0). It should be noted...