Author name code: kitiashvili ADS astronomy entries on 2022-09-14 author:"Kitiashvili, Irina N." ------------------------------------------------------------------------ Title: Physics-based Modeling of Multiscale Solar Dynamics for Understanding Origins of Space Weather Disturbances Authors: Kitiashvili, Irina; Sadykov, Viacheslav; Wray, Alan; Kosovichev, Alexander Bibcode: 2022cosp...44.3232K Altcode: Forecasting space weather on different temporal scales is a problem that requires the development of advanced physics-based models, algorithms, and data analysis approaches for a variety of observations and their inferences. We take advantage of currently available computational capabilities to model solar dynamics from the deep interior to the corona and investigate mechanisms that may drive space weather conditions. Comparison of the synthetic observables obtained from numerical simulations and actual observations allows us to uncover physical processes associated with observed phenomena. To facilitate a transition from modeling short-term physical phenomena to developing a reliable forecast-oriented model, we suggest using the data assimilation approach. It allows us to cross-analyze dynamo model solutions and observations and to consider possible uncertainties and errors. Our results demonstrate promising potential for modeling upcoming solar activity combined with observations. In this presentation, we briefly summarize current multi-scale modeling capabilities and results and discuss ongoing developments to build a reliable physics-based forecast-oriented model of solar activity. Title: Using 3D Realistic Modeling of Solar-Type Stars to Characterize Stellar Jitter Authors: Kitiashvili, Irina; Wray, Alan; Granovsly, Samuel Bibcode: 2022cosp...44..587K Altcode: Detection of Earth-mass exoplanets orbiting solar-type stars requires a procedure to extract weak variations in the radial velocity signals, which are significantly weaker than the background noise induced by dynamics of the stellar photospheres. We use the 3D radiative MHD "StellarBox" code to characterize this noise to obtain realistic stellar (magneto)convection models based on first physical principles. We performed a series of high-resolution numerical simulations of solar-type stars to obtain disk-integrated synthetic observations by computing Fe I lines using the radiative transfer "Spinor" code. We present the stellar jitter modeling results for selected target stars and discuss the origin of the noise and perspectives of this effort. Title: Characterization of Stellar Jitter Using 3D Realistic Modeling of Solar-Type Stars Authors: Kitiashvili, Irina; Granovsky, Samuel; Wray, Alan; Kosovichev, Alexander Bibcode: 2022AAS...24041702K Altcode: Recent progress in the ab-initio modeling of solar magnetoconvection makes it possible to simulate the surface dynamics of solar-type stars with a high degree of realism. These simulations can be used to characterize stellar photospheric disturbances which contaminate the radial velocity signal and limit our capabilities to detect Earth-mass exoplanets. We use the 3D radiative MHD "StellarBox" code to obtain realistic stellar (magneto)convection models and characterize photospheric noise. The initial conditions for the numerical simulations are generated using the MESA stellar evolution code. The computational domain covers the upper layers of the convection zone and the lower atmosphere. We present numerical models of solar-type planet-host stars, disk-integrated synthetic observations, and observables such as line profiles, Doppler shift, etc. Synthesis of observations performed for a list of FeI lines using the radiative transfer "Spinor" code. We present the stellar jitter modeling results for selected target stars, discuss the origin of the noise and compare with high-resolution HARPS observations. Title: Leptocline as a Shallow Substructure of Near-Surface Shear Layer in 3D Radiative Hydrodynamic Simulations Authors: Kitiashvili, Irina N.; Kosovichev, Alexander G.; Wray, Alan A.; Sadykov, Viacheslav M.; Guerrero, Gustavo Bibcode: 2022arXiv220301484K Altcode: Understanding effects driven by rotation in the solar convection zone is essential for many problems related to solar activity, such as the formation of differential rotation, meridional circulation, and others. We analyze realistic 3D radiative hydrodynamics simulations of solar subsurface dynamics in the presence of rotation in a local domain 80 Mm wide and 25 Mm deep, located at 30 degrees latitude. The simulation results reveal the development of a shallow 10-Mm deep substructure of the Near-Surface Shear Layer (NSSL), characterized by a strong radial rotational gradient and self-organized meridional flows. This shallow layer ("leptocline") is located in the hydrogen ionization zone associated with enhanced anisotropic overshooting-type flows into a less unstable layer between the H and HeII ionization zones. We discuss current observational evidence of the presence of the leptocline and show that the radial variations of the differential rotation and meridional flow profiles obtained from the simulations in this layer qualitatively agree with helioseismic observations. Title: Revisiting the Solar Research Cyberinfrastructure Needs: A White Paper of Findings and Recommendations Authors: Nita, Gelu; Ahmadzadeh, Azim; Criscuoli, Serena; Davey, Alisdair; Gary, Dale; Georgoulis, Manolis; Hurlburt, Neal; Kitiashvili, Irina; Kempton, Dustin; Kosovichev, Alexander; Martens, Piet; McGranaghan, Ryan; Oria, Vincent; Reardon, Kevin; Sadykov, Viacheslav; Timmons, Ryan; Wang, Haimin; Wang, Jason T. L. Bibcode: 2022arXiv220309544N Altcode: Solar and Heliosphere physics are areas of remarkable data-driven discoveries. Recent advances in high-cadence, high-resolution multiwavelength observations, growing amounts of data from realistic modeling, and operational needs for uninterrupted science-quality data coverage generate the demand for a solar metadata standardization and overall healthy data infrastructure. This white paper is prepared as an effort of the working group "Uniform Semantics and Syntax of Solar Observations and Events" created within the "Towards Integration of Heliophysics Data, Modeling, and Analysis Tools" EarthCube Research Coordination Network (@HDMIEC RCN), with primary objectives to discuss current advances and identify future needs for the solar research cyberinfrastructure. The white paper summarizes presentations and discussions held during the special working group session at the EarthCube Annual Meeting on June 19th, 2020, as well as community contribution gathered during a series of preceding workshops and subsequent RCN working group sessions. The authors provide examples of the current standing of the solar research cyberinfrastructure, and describe the problems related to current data handling approaches. The list of the top-level recommendations agreed by the authors of the current white paper is presented at the beginning of the paper. Title: Modeling Stellar Jitter for the Detection of Earth-Mass Exoplanets via Precision Radial Velocity Measurements Authors: Granovsky, Samuel; Kitiashvili, Irina N.; Wray, Alan Bibcode: 2022arXiv220207087G Altcode: The detection of Earth-size exoplanets is a technological and data analysis challenge. Future progress in Earth-mass exoplanet detection is expected from the development of extreme precision radial velocity measurements. Increasing radial velocity precision requires developing a new physics-based data analysis methodology to discriminate planetary signals from host-star-related effects, taking stellar variability and instrumental uncertainties into account. In this work, we investigate and quantify stellar disturbances of the planet-hosting solar-type star HD121504 from 3D radiative modeling obtained with the StellarBox code. The model has been used for determining statistical properties of the turbulent plasma and obtaining synthetic spectroscopic observations for several Fe I lines at different locations on the stellar disk to mimic high-resolution spectroscopic observations. Title: Physical Properties of the Solar Atmosphere Derived from Comparison of Spectro-Polarimetric SDO/HMI Observables with 3D Radiative MHD Simulations Authors: Sadykov, Viacheslav; Kitiashvili, Irina; Kosovichev, Alexander; Wray, Alan Bibcode: 2021AGUFMSH44A..06S Altcode: In this study, we compare the SDO/HMI line-of-sight observables (magnetic field, velocity, continuum intensity, and line depth) with the related physical properties for dynamo simulations performed using the StellarBox 3D Radiative MHD code. The modeling of the Fe I 6173 A Stokes profiles is performed using the SPINOR radiative transfer code in the LTE approximation. The reproduced SDO/HMI line-of-sight pipeline is applied to the modeled spectra, and the observables are synthesized with high (numerical) and SDO/HMI (instrumental) resolutions. Correlations between the observables and the physical properties at various heights in the atmosphere are studied for a set of view angles (0, 30, 45, 60, 70, and 80 degrees away from the solar disk center). It is found that SDO/HMI velocity and magnetic field (less prominently) observables are correlated with physical parameters at certain heights of the solar atmosphere. These heights increase from about 100-150 km above the photosphere for the disk center case to 300-600 km above the photosphere for the 80-degree case, however, are almost the same for the 0-60 degree projection angles. The integrated unsigned magnetic flux calculated from the observables underestimates the actual magnetic flux at strongest correlation heights for about 40% on average. The integrated continuum intensity as calculated from the observables is about 4-8% larger with respect to its actual values. In addition, we discuss a problem of contribution of unresolved magnetic elements to solar brightness based on the modeling data. The results improve physics-based interpretations of the SDO/HMI observables and provide a better understanding of the physical properties of the solar atmosphere. Title: 3D Radiative MHD Modeling of the Solar Atmospheric Dynamics and Structure Authors: Kitiashvili, Irina; Sadykov, Viacheslav; Wray, Alan; Kosovichev, Alexander Bibcode: 2021AGUFMSH45B2370K Altcode: Dramatic dynamical phenomena accompanied by strong thermodynamic and magnetic structuring are the primary drivers of great interest in studying the solar atmosphere with high spatial and temporal resolutions. Using current computational capabilities, it became possible to model the magnetized solar plasma in different regimes with a high degree of realism. To study the fine structuring of the solar atmosphere and dynamics, we use 3D MHD radiative models covering all layers from the upper convection zone to the corona. Realistic 3D radiative MHD modeling of the solar magnetoconvection and atmosphere allows us to generate synthetic observables that directly link the physical properties of the solar plasma to spectroscopic observables. We calculate series of synthetic spectropolarimetric imaging data that model observations from different space instruments: HMI and AIA (SDO), SOT (Hinode), and IRIS, as well as for the upcoming DKIST ground observations, and investigate how the observational data are linked to physical processes in the solar atmosphere. In the presentation, we discuss qualitative and quantitative changes of the atmospheric structure and dynamics at different layers of the solar atmosphere, properties of acoustic and surface gravity waves, sources of the local heating in the chromosphere-corona transition region, formation of shocks, and high-frequency oscillations in the corona, as well as manifestation of these phenomena in the modeled observables. Title: Dynamical Coupling of the Solar Subsurface Shear Layer and the Atmosphere Authors: Kitiashvili, Irina; Sadykov, Viacheslav; Kosovichev, Alexander; Wray, Alan Bibcode: 2021AGUFMSH53C..01K Altcode: The dynamical coupling of subsurface and surface layers of the Sun is crucial for understanding how phenomena observed in the solar atmosphere reflect the evolution of subsurface plasma flows in the present global-scale rotation. In this work, we use long time-series (over 100-hours) of high-resolution 3D radiative hydrodynamic simulations obtained for an 80-Mm wide and 25-Mm deep computational domain, using the SolarBox code, to investigate the formation and dynamics of the Subsurface Shear Layer (SSL) and observational manifestations. The solar rotation is modeled in the f-plane approximation at 30 degrees latitude. The simulation results reveal the formation of the SSL, and meridional circulation. To compare the simulation results with the SDO/HMI observations, we generate synthetic time series of the Fe I (6173A) line profile for different locations on the solar disk, using the SPINOR radiative transfer code. The line-profile data are converted into the SDO/HMI observables using an HMI pipeline emulator and analyzed for both the modeled and instrumental resolutions. The analysis results reproduce the photospheric structure and dynamics as well as various helioseismic properties such as rotational frequency splitting, ring- and time-distance diagrams, and the center-to-limb effect. This work provides a basis for a deeper understanding of the solar subsurface dynamics and physical interpretation of observational data. Title: Simulating Exoplanet Host Star -Horologii from the Surface to the Bottom of the Convection Zone Authors: Guerrero, Gustavo; Kitiashvili, Irina; Bonanno, Alfio; Kosovichev, Alexander Bibcode: 2021AGUFM.U44B..02G Altcode: The G0 type, planet-hosting, star -Horologii has been observed for several years through different techniques. While there is still some debate about its rotational period (4-8 days), it seems conclusive that it exhibits a magnetic cycle of ~1.6 years. This short period allowed for constructing the first butterfly diagram for a star different from the Sun. The detailed study of this object provides unique opportunities to understand the dynamo operating in solar-like stars. In this work, we present realistic 3D radiative hydrodynamics simulations (RHD) of surface and subsurface convection of this star. The depth reached by these models connects with anelastic global MHD simulations (AMHD) of the -Horologiis dynamo. The RHD models provide an understanding of the structure and signal of surface convection and its spectra, allowing for direct comparison with high-resolution spectroscopic observations. The AMHD simulations enlighten the magnetic contribution to this signal. In addition, we provide predictions of the star differential rotation, meridional circulation and the alpha-Omega dynamo sustaining its magnetic field. Title: Effects of observational data shortage on accuracy of global solar activity forecast Authors: Kitiashvili, Irina N. Bibcode: 2021MNRAS.505.6085K Altcode: 2020arXiv200109376K Building a reliable forecast of solar activity is a long-standing problem that requires an accurate description of past and current global dynamics. Relatively recently, synoptic observations of magnetic fields and subsurface flows have become available. In this paper, we present an investigation of the effects of short observational data series on the accuracy of solar cycle prediction. This analysis is performed using the annual sunspot number time-series applied to the Parker-Kleeorin-Ruzmaikin dynamo model and employing the Ensemble Kalman Filter (EnKF) data assimilation method. The testing of cycle prediction accuracy is performed for the last six cycles (for Solar Cycles 19-24) by sequentially shortening the observational data series to predict a target cycle and evaluate the resulting prediction accuracy according to specified criteria. According to the analysis, reliable activity predictions can be made using relatively short time-series of the sunspot number. The accuracy of the solar activity has a weak dependence on the length of available observations. It is demonstrated that at least three cycles of observations are needed to obtain robust forecasts. Title: Dynamics and Structure of Main-Sequence Stars with Shallow Convection Zones Authors: Kitiashvili, I. N.; Wray, A. A. Bibcode: 2021tsc2.confE.132K Altcode: A dramatic increase in observational data from NASA's Kepler, K2, and TESS missions and supporting ground-based observatories have opened new opportunities to investigate the internal structure, dynamics, and evolution of stars and their atmospheres. We present 3D radiative MHD simulations for several main-sequence stars with masses from 1.4 to 1.5 Msun. The simulations are performed using the "StellarBox" code developed for modeling stellar turbulent convection and atmospheres with a high degree of realism. This presentation discusses similarities and differences between 3D realistic-type and 1D mixing-length models with regard to structural, thermodynamic, and turbulent property variations from the radiative zone to the convection zone and photosphere. Title: Probing Stellar Cores by Asteroseismic Inversions Authors: Kosovichev, Alexander; Kitiashvili, Irina Bibcode: 2021tsc2.confE.130K Altcode: Precision asteroseismology data from Kepler and TESS provide a unique opportunity to investigate the interior structure of stars at various stages of stellar evolution. Detection of mixed acoustic-gravity oscillation modes has opened perspectives for probing the properties of energy-generating cores. Most of the previous analysis was focused on fitting standard evolutionary stellar models using mode frequency splitting and scaling laws for oscillation properties. We present direct asteroseismic inversions using the method of optimally localized averages, which effectively eliminates the surface effects and attempts to resolve the stellar core structure. Title: 3D Modeling of Solar-Type Stars to Characterize Stellar Jitter Authors: Kitiashvili, I. N.; Wray, A. A.; Granovsky, S. Bibcode: 2021tsc2.confE.135K Altcode: Detection of Earth-mass planets requires measurements of radial velocity with extreme precision. To capture the tiny disturbances caused by a planet's motion, it is necessary to understand and characterize the host star's turbulent dynamics in order to apply proper filtering to the observational data. We take advantage of current computational and technological capabilities to develop 3D realistic models of the stellar subsurface convection and atmospheres and thereby estimate the photospheric jitter. We have identified an initial set of target stars, obtained initial conditions using the MESA code, and obtained initial 3D radiative models of the stellar surfaces and atmospheres with a spatial resolution of 50km. We present initial 3D radiative hydrodynamic model results of the planet-hosting star HD209458. Title: Prediction of Solar Proton Events with Machine Learning: Comparison with Operational Forecasts and "All-Clear" Perspectives Authors: Sadykov, Viacheslav; Kosovichev, Alexander; Kitiashvili, Irina; Oria, Vincent; Nita, Gelu M; Illarionov, Egor; O'Keefe, Patrick; Jiang, Yucheng; Fereira, Sheldon; Ali, Aatiya Bibcode: 2021arXiv210703911S Altcode: Solar Energetic Particle events (SEPs) are among the most dangerous transient phenomena of solar activity. As hazardous radiation, SEPs may affect the health of astronauts in outer space and adversely impact current and future space exploration. In this paper, we consider the problem of daily prediction of Solar Proton Events (SPEs) based on the characteristics of the magnetic fields in solar Active Regions (ARs), preceding soft X-ray and proton fluxes, and statistics of solar radio bursts. The machine learning (ML) algorithm uses an artificial neural network of custom architecture designed for whole-Sun input. The predictions of the ML model are compared with the SWPC NOAA operational forecasts of SPEs. Our preliminary results indicate that 1) for the AR-based predictions, it is necessary to take into account ARs at the western limb and on the far side of the Sun; 2) characteristics of the preceding proton flux represent the most valuable input for prediction; 3) daily median characteristics of ARs and the counts of type II, III, and IV radio bursts may be excluded from the forecast without performance loss; and 4) ML-based forecasts outperform SWPC NOAA forecasts in situations in which missing SPE events is very undesirable. The introduced approach indicates the possibility of developing robust "all-clear" SPE forecasts by employing machine learning methods. Title: Influence of Center-to-Limb Effects on Observations of the Solar Atmosphere Authors: Kitiashvili, I. N.; Sadykov, V. M.; Wray, A. A. Bibcode: 2021AAS...23811313K Altcode: The complexity of the highly dynamical atmospheric layers of the Sun in the presence of inhomogeneous magnetic fields makes it challenging to correctly interpret observations from space and ground-based instruments. In particular, the center-to-limb variations of spectro-polarimetric properties may lead to significant misinterpretations of helioseismic and magnetic observables. To address these challenges and study the physical processes behind observations of various types, we use 3D MHD radiative models, which reproduce the dynamics and observational properties with high-degree realism. To study the center-to-limb effects, we obtained series of synthetic spectropolarimetric and intensity imaging data that mimic observations from different space instruments: HMI and AIA (SDO), SOT (Hinode), and IRIS, as well as upcoming DKIST ground observations. In the presentation, we discuss the influence of observations at different angular distances from the solar disk center on the resulting properties of the magnetic field, atmospheric structure and dynamics, and acoustic and surface gravity waves. Title: Physical Properties of the Solar Atmosphere Derived from Comparison of Spectro-Polarimetric SDO/HMI Observables with 3D Radiative MHD Simulations Authors: Sadykov, V.; Kitiashvili, I.; Kosovichev, A.; Wray, A. Bibcode: 2021AAS...23832804S Altcode: In this study, we compare the SDO/HMI line-of-sight observables (magnetic field, velocity, continuum intensity, and line depth) with the related physical properties for several dynamo simulation runs performed using the "StellarBox" 3D Radiative MHD code. The modeling of the Fe I 6173 Å Stokes profiles is performed using the SPINOR radiative transfer code in the LTE approximation. The reproduced SDO/HMI line-of-sight pipeline is applied to the modeled spectra, and the observables are synthesized with high (numerical) and SDO/HMI (instrumental) resolutions. Correlations between the observables and the physical properties at various heights in the atmosphere are studied for a set of view angles (0, 30, 45, 60, 70, and 80 degrees away from the solar disk center). It is found that the SDO/HMI magnetic field and velocity measurements are unambiguously correlated with physical parameters at certain heights of the solar atmosphere. These heights increase from about 100 km above the photosphere for the disk center case to 300-600 km above the photosphere for the 80-degree case. The heights are found to be slightly lower in regions where stronger magnetic fields are found. The comparison of the photospheric magnetic flux and integrated continuum intensity derived from the SDO/HMI observables and high-resolution observations and spectra is discussed. The results of our study improve physics-based interpretations of the SDO/HMI observables and provide a better understanding of the physical properties of the solar atmosphere. Title: Understanding the Consequences Of Fields and Flows in the Interior and Exterior of the Sun (COFFIES) Authors: Hoeksema, J. T.; Brummell, N.; Bush, R.; Hess Webber, S.; Kitiashvili, I.; Komm, R.; Kosovichev, A.; Mendez, B.; Scherrer, P.; Upton, L.; Wray, A.; Zevin, D.; The Coffies Team Bibcode: 2021AAS...23811322H Altcode: The solar activity cycle is the Consequence Of Fields and Flows in the Interior and Exterior of the Sun (COFFIES). As a Phase-1 NASA DRIVE Science Center (DSC), COFFIES ultimately aims to develop a data-driven model of solar activity. To attain this goal COFFIES members are learning to work together effectively to perform the investigations needed to answer five primary science questions:

1) What drives varying large-scale motions in the Sun?

2) How do flows interact with the magnetic field to cause varying activity cycles?

3) Why do active regions emerge when and where they do?

4) What do the manifestations of activity and convection reveal about the internal processes?

5) How does our understanding of the Sun as a star inform us more generally about activity dynamics and structure?

The virtual COFFIES center brings together a broad spectrum of observers, data analysts, theorists, computational scientists, and educators who collaborate through interacting working groups of four principal science teams. The principal objectives of the four primary science teams are to 1) understand the generation of quasi-periodic stellar magnetic cycles, 2) further develop 3D physical models of interior dynamics and convection, 3) establish clear physical links between solar flow fields and near-surface observations, and 4) develop more robust helioseismic techniques to resolve solar interior flows. Additional cross-team activities are facilitated by teams for numerical modeling, center effectiveness, outreach and eduction, and diversity, equity, inclusion and access (DEIA). Title: Compression of Solar Spectroscopic Observations: a Case Study of Mg II k Spectral Line Profiles Observed by NASA's IRIS Satellite Authors: Sadykov, Viacheslav M; Kitiashvili, Irina N; Sainz Dalda, Alberto; Oria, Vincent; Kosovichev, Alexander G; Illarionov, Egor Bibcode: 2021arXiv210307373S Altcode: In this study we extract the deep features and investigate the compression of the Mg II k spectral line profiles observed in quiet Sun regions by NASA's IRIS satellite. The data set of line profiles used for the analysis was obtained on April 20th, 2020, at the center of the solar disc, and contains almost 300,000 individual Mg II k line profiles after data cleaning. The data are separated into train and test subsets. The train subset was used to train the autoencoder of the varying embedding layer size. The early stopping criterion was implemented on the test subset to prevent the model from overfitting. Our results indicate that it is possible to compress the spectral line profiles more than 27 times (which corresponds to the reduction of the data dimensionality from 110 to 4) while having a 4 DN average reconstruction error, which is comparable to the variations in the line continuum. The mean squared error and the reconstruction error of even statistical moments sharply decrease when the dimensionality of the embedding layer increases from 1 to 4 and almost stop decreasing for higher numbers. The observed occasional improvements in training for values higher than 4 indicate that a better compact embedding may potentially be obtained if other training strategies and longer training times are used. The features learned for the critical four-dimensional case can be interpreted. In particular, three of these four features mainly control the line width, line asymmetry, and line dip formation respectively. The presented results are the first attempt to obtain a compact embedding for spectroscopic line profiles and confirm the value of this approach, in particular for feature extraction, data compression, and denoising. Title: Effects of Rotation on Internal Structure and Dynamics of Main-Sequence Stars Authors: Kitiashvili, Irina N.; Wray, Alan A. Bibcode: 2021csss.confE..17K Altcode: Current state-of-the-art computer simulations allow us to build 3D dynamical and radiative models of stars from physical first principles with a high degree of realism. The radiative 3D dynamical stellar models obtained with the StellarBox code take into account the effects of turbulence, stellar abundances, a realistic equation of state, and radiative energy transport. In this talk, I will discuss the effects of rotation on the turbulent dynamics and surface structure for a 1.47 Msun star for rotational periods of 1 and 14 days. The simulations are performed with the computational domain at various latitudes. The models reproduce stellar granulation, the subsurface shear layer, structural changes in convection, and the tachocline, which is the interface between the inner radiative zone and the outer convection zone and plays a crucial role in stellar variability. In particular, the model results reveal the formation of differential rotation and meridional circulation. Title: Connecting Atmospheric Properties and Synthetic Emission of Shock Waves Using 3D RMHD Simulations of the Quiet Sun Authors: Sadykov, Viacheslav M.; Kitiashvili, Irina N.; Kosovichev, Alexander G.; Wray, Alan A. Bibcode: 2021ApJ...909...35S Altcode: 2020arXiv200805995S We analyze the evolution of shock waves in high-resolution 3D radiative MHD simulations of the quiet Sun and their synthetic emission characteristics. The simulations model the dynamics of a 12.8 × 12.8 × 15.2 Mm quiet-Sun region (including a 5.2 Mm layer of the upper convection zone and a 10 Mm atmosphere from the photosphere to corona) with an initially uniform vertical magnetic field of 10 G, naturally driven by convective flows. We synthesize the Mg II and C II spectral lines observed by the Interface Region Imaging Spectrograph (IRIS) satellite and extreme ultraviolet emission observed by the Solar Dynamics Observatory (SDO)/AIA telescope. Synthetic observations are obtained using the RH1.5D radiative transfer code and temperature response functions at both the numerical and instrumental resolutions. We found that the Doppler velocity jumps of the C II 1334.5 Å IRIS line and a relative enhancement of the emission in the 335 Å SDO/AIA channel are the best proxies for the enthalpy deposited by shock waves into the corona (with Kendall's τ correlation coefficients of 0.59 and 0.38, respectively). The synthetic emission of the lines and the extreme ultraviolet passbands are correlated with each other during the shock-wave propagation. All studied shocks are mostly hydrodynamic (i.e., the magnetic energy carried by horizontal fields is ≤2.6% of the enthalpy for all events) and have Mach numbers >1.0-1.2 in the low corona. The study reveals the possibility of diagnosing energy transport by shock waves into the solar corona, as well as their other properties, by using IRIS and SDO/AIA sensing observations. Title: 3D Realistic Modeling of Main-Sequence Stars with Shallow Outer Convection Zone Authors: Kitiashvili, I. N.; Wray, A. A.; Kosovichev, A. G. Bibcode: 2021AAS...23741505K Altcode: Our current state-of-the-art computer simulations allow us to build 3D dynamical and radiation models of F-type stars from physical first principles. Using the stellar interior's structure from the MESA stellar evolution code as initial conditions, we generate models of main-sequence stars with the mass from 1.4 Msun to 2 Msun for various metallicity composition, in the range of [Fe/H] from -0.3 to 0.2. The radiative 3D dynamical stellar models obtained with the StellarBox code take into account the effects of turbulence, stellar abundances, and radiation. We investigate the turbulent dynamics from the radiative zone to the outer convection zone and the lower atmosphere for these stars and compare their turbulent properties.

Also, we investigate the effects of stellar rotation for a 1.47Msun star for rotational periods of 1 and 14 days. The simulations are performed for the different latitudinal location of the computation domain. The models reproduce the subsurface shear layer, structural changes of convection, and the tachocline, which is the interface between the inner radiative zone and the outer convection zone and plays a crucial role in stellar variability. In particular, the model results reveal the formation of differential rotation of an anti-solar type. The simulation results shed light on differential rotation properties, the excitation of oscillation modes, the tachocline's dynamics and structure, and support analysis and interpretation of observational data from Kepler and TESS missions. Title: Radiation Data Portal: Integration of Radiation Measurements at the Aviation Altitudes and Solar-Terrestrial Environment Observations Authors: Sadykov, V. M.; Kitiashvili, I. N.; Tobiska, W. K.; Guhathakurta, M. Bibcode: 2021SpWea..1902653S Altcode: 2021arXiv210307604S The impact of radiation dramatically increases at high altitudes in the Earth's atmosphere and in space. Therefore, monitoring and access to radiation environment measurements are critical for estimating the radiation exposure risks of aircraft and spacecraft crews and the impact of space weather disturbances on electronics. Addressing these needs requires convenient access to multisource radiation environment data and enhancement of visualization and search capabilities. The Radiation Data Portal represents an interactive web-based application for search and visualization of in-flight radiation measurements. The portal enhances the exploration capabilities of various properties of the radiation environment and provides measurements of dose rates along with information on space weather-related conditions. The Radiation Data Portal back-end is a MySQL relational database that contains the radiation measurements obtained from the Automated Radiation Measurements for Aerospace Safety (ARMAS) device and the soft X-ray and proton flux measurements from the Geostationary Operational Environmental Satellite. The implemented application programming interface and Python routines allow a user to retrieve the database records without interaction with the web interface. As a use case of the Radiation Data Portal, we examine ARMAS measurements during an enhancement of the solar proton (SP) fluxes, known as solar proton events, and compare them to measurements during SP-quiet periods. Title: Radiation Portal: Connection of Radiation Measurements on Airplane Flights with Observations of Solar-Terrestrial Environment Authors: Sadykov, V. M.; Kitiashvili, I.; Tobiska, W. K.; Guhathakurta, M. Bibcode: 2020AGUFMSH0030002S Altcode: The impact of solar radiation dramatically increases at high altitudes in the Earth's atmosphere and in space. Therefore, continuous monitoring of the radiation environment is critical for the safety of aircraft and spacecraft crews and passengers. Addressing the problem requires a complex approach of integration of different data sources and enhancement of the visualization and search capabilities. The Radiation Portal Database represents an interactive web-based application for convenient search and visualization of in-flight radiation measurements and exploration of various properties related to the radiation environment. The primary element of the Radiation Portal back-end is a MySQL relational database that currently contains the radiation measurements obtained from the Automated Radiation Measurements for Aerospace Safety (ARMAS) device, and soft X-ray and proton fluxes from Geostationary Orbiting Environmental Satellite (GOES). The developed Application Programming Interface (API) and related Python routines allow a user to retrieve the database records directly and efficiently, without interaction with the web interface. As a use case of the Radiation Portal, we examine the properties of the ARMAS flights taken during the enhanced Solar Proton (SP) fluxes and compare them to the flights of similar time and location taken during SP-quiet periods. Title: Helioseismic Constraints on the Solar Interior Dynamics and Dynamo Authors: Kosovichev, A. G.; Brummell, N.; Dikpati, M.; Guerrero, G.; Kitiashvili, I.; Komm, R.; Korzennik, S.; Pipin, V.; Reiter, J.; Stejko, A.; Ulrich, R. K.; Warnecke, J. Bibcode: 2020AGUFMSH007..04K Altcode: Uninterrupted helioseismic observations from the SoHO/MDI, SDO/HMI and GONG instruments for more than two decades provide unique observational data for studying the solar-cycle variations of the differential rotation, large-scale and meridional flows. The data also allows us to investigate changes in the thermodynamic structure associated with dynamo-generated magnetic fields. The wealth of global and local helioseismic data provides theoretical constraints on the solar dynamics and dynamo models. The synergy of helioseismic inferences with advanced MHD modeling sheds light on the origin of the solar activity cycles. It helps to understand better the physical processes that control the strength and duration of the cyclic magnetic activity and leads to new physics-based approaches for prediction of the solar cycles. We briefly overview the current status, discuss the solar dynamical structure and evolution revealed by helioseismic inversions and the forward-modeling method, and focus on the most critical points of the problem. In particular, we discuss recent advances in measurements and modeling of the solar-cycle variations of the meridional circulation and migrating zonal flows (torsional oscillations) on the solar surface and in the subsurface layers, the deep convection zone, and the solar tachocline. The relationships between the internal dynamics and the evolution of global magnetic fields lead to new ideas of how magnetic fields are generated and affect the solar flows and structure. Title: Multi-Wavelength Modeling and Analysis of the Center-to-Limb Effects of Solar Spectroscopy and Helioseismology Authors: Kitiashvili, I.; Zhao, J.; Sadykov, V. M.; Criscuoli, S.; Kosovichev, A. G.; Wray, A. A. Bibcode: 2020AGUFMSH0020003K Altcode: An accurate interpretation of observed solar dynamics with different instruments requires modeling solar magnetoconvection in different regimes, as well as taking into account center-to-limb effects, magnetic fields, and turbulence. Realistic 3D radiative MHD modeling of the solar magnetoconvection and atmosphere allows us to generate synthetic observables that directly link the physical properties of the solar plasma to spectroscopic and helioseismic observables. In this work, we investigate the influence of the center-to-limb effects for a wide range of wavelengths, which correspond to the operational lines of HMI/SDO, Hinode, DKIST, and other instruments. In particular, we discuss the wavelength-dependency of the center-to-limb helioseismic observations of acoustic travel times that are used for diagnostics of the deep meridional circulation, as well as 'concave' Sun effect. The presented study will support interpretation of helioseismic inversion results by taking into account realistic coupling of subsurface and atmosphere, and geometry-related effects. In particular, it allows us to improve accuracy of solar subsurface measurements from the SoHO and SDO missions, and resolve the long-standing problem of the meridional circulation and evolution with the solar cycle. Title: Machine Learning in Heliophysics and Space Weather Forecasting: A White Paper of Findings and Recommendations Authors: Nita, Gelu; Georgoulis, Manolis; Kitiashvili, Irina; Sadykov, Viacheslav; Camporeale, Enrico; Kosovichev, Alexander; Wang, Haimin; Oria, Vincent; Wang, Jason; Angryk, Rafal; Aydin, Berkay; Ahmadzadeh, Azim; Bai, Xiaoli; Bastian, Timothy; Filali Boubrahimi, Soukaina; Chen, Bin; Davey, Alisdair; Fereira, Sheldon; Fleishman, Gregory; Gary, Dale; Gerrard, Andrew; Hellbourg, Gregory; Herbert, Katherine; Ireland, Jack; Illarionov, Egor; Kuroda, Natsuha; Li, Qin; Liu, Chang; Liu, Yuexin; Kim, Hyomin; Kempton, Dustin; Ma, Ruizhe; Martens, Petrus; McGranaghan, Ryan; Semones, Edward; Stefan, John; Stejko, Andrey; Collado-Vega, Yaireska; Wang, Meiqi; Xu, Yan; Yu, Sijie Bibcode: 2020arXiv200612224N Altcode: The authors of this white paper met on 16-17 January 2020 at the New Jersey Institute of Technology, Newark, NJ, for a 2-day workshop that brought together a group of heliophysicists, data providers, expert modelers, and computer/data scientists. Their objective was to discuss critical developments and prospects of the application of machine and/or deep learning techniques for data analysis, modeling and forecasting in Heliophysics, and to shape a strategy for further developments in the field. The workshop combined a set of plenary sessions featuring invited introductory talks interleaved with a set of open discussion sessions. The outcome of the discussion is encapsulated in this white paper that also features a top-level list of recommendations agreed by participants. Title: Response of SDO/HMI Observables to Heating of the Solar Atmosphere by Precipitating High-energy Electrons Authors: Sadykov, Viacheslav M.; Kosovichev, Alexander G.; Kitiashvili, Irina N.; Kerr, Graham S. Bibcode: 2020ApJ...893...24S Altcode: 2019arXiv190610788S We perform an analysis of the line-of-sight (LOS) observables of the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) for models of the solar atmosphere heated by precipitating high-energy electrons during solar flares. The radiative hydrodynamic (RADYN) flare models are obtained from the F-CHROMA database. The Stokes profiles for the Fe 6173 Å line observed by SDO/HMI are calculated using the radiative transfer code RH1.5D, assuming statistical equilibrium for atomic level populations, and imposing uniform background vertical magnetic fields of various strengths. The SDO/HMI observing sequence and LOS data processing pipeline algorithm are applied to derive the observables (continuum intensity, line depth, Doppler velocity, LOS magnetic field). Our results reveal that the strongest deviations of the observables from the actual spectroscopic line parameters are found for the model with a total energy deposited of Etotal = 1.0 × 1012 erg cm-2, injected with a power-law spectral index of δ = 3 above a low-energy cutoff of Ec = 25 keV. The magnitudes of the velocity and magnetic field deviations depend on the imposed magnetic field, and can reach 0.35 km s-1 for LOS velocities, 90 G for LOS magnetic field, and 3% for continuum enhancement for the 1000 G imposed LOS magnetic field setup. For Etotal ≥ 3.0 × 1011 erg cm-2 models, the velocity and magnetic field deviations are most strongly correlated with the energy flux carried by ∼50 keV electrons, and the continuum enhancement is correlated with the synthesized ∼55-60 keV hard X-ray photon flux. The relatively low magnitudes of perturbations of the observables and absence of magnetic field sign reversals suggest that the considered RADYN beam heating models augmented with the uniform vertical magnetic field setups cannot explain the strong transient changes found in the SDO/HMI observations. Title: Application of Synoptic Magnetograms to Global Solar Activity Forecast Authors: Kitiashvili, I. N. Bibcode: 2020ApJ...890...36K Altcode: 2019arXiv191000820K Synoptic magnetograms provide us with knowledge about the evolution of magnetic fields on the solar surface and present important information for forecasting future solar activity. In this work, poloidal and toroidal magnetic field components derived from synoptic magnetograms are assimilated, using the Ensemble Kalman Filter method, into a mean-field dynamo model based on Parker's migratory dynamo theory complemented by magnetic helicity conservation. It was found that the predicted toroidal field is in good agreement with observations for almost the entire following solar cycle. However, poloidal field predictions agree with observations only for the first 2-3 yr of the predicted cycle. The results indicate that the upcoming Solar Maximum of Cycle 25 (SC25) is expected to be weaker than the current Cycle 24. The model results show that a deep extended solar activity minimum is expected during 2019-2021, and that the next solar maximum will occur in 2024-2025. The sunspot number at the maximum will be about 50 with an error estimate of 15%-30%. The maximum will likely have a double peak or show extended periods (for 2-2.5 yr) of high activity. According to the hemispheric prediction results, SC25 will start in 2020 in the southern hemisphere, and will have a maximum in 2024 with a sunspot number of about 28. In the northern hemisphere the cycle will be delayed for about 1 yr (with an error of ±0.5 yr), and reach a maximum in 2025 with a sunspot number of about 23. Title: Resolving Power of Asteroseismic Inversion of the Kepler Legacy Sample Authors: Kosovichev, Alexander G.; Kitiashvili, Irina N. Bibcode: 2020IAUS..354..107K Altcode: 2020arXiv200209839K The Kepler Asteroseismic Legacy Project provided frequencies, separation ratios, error estimates, and covariance matrices for 66 Kepler main sequence targets. Most of the previous analysis of these data was focused on fitting standard stellar models. We present results of direct asteroseismic inversions using the method of optimally localized averages (OLA), which effectively eliminates the surface effects and attempts to resolve the stellar core structure. The inversions are presented for various structure properties, including the density stratification and sound speed. The results show that the mixed modes observed in post-main sequence F-type stars allow us to resolve the stellar core structure and reveal significant deviations from the evolutionary models obtained by the grid-fitting procedure to match the observed oscillation frequencies. Title: Global evolution of solar magnetic fields and prediction of activity cycles Authors: Kitiashvili, Irina N. Bibcode: 2020IAUS..354..147K Altcode: 2020arXiv200304563K Prediction of solar activity cycles is challenging because physical processes inside the Sun involve a broad range of multiscale dynamics that no model can reproduce and because the available observations are highly limited and cover mostly surface layers. Helioseismology makes it possible to probe solar dynamics in the convective zone, but variations in differential rotation and meridional circulation are currently available for only two solar activity cycles. It has been demonstrated that sunspot observations, which cover over 400 years, can be used to calibrate the Parker-Kleeorin-Ruzmaikin dynamo model, and that the Ensemble Kalman Filter (EnKF) method can be used to link the modeled magnetic fields to sunspot observations and make reliable predictions of a following activity cycle. However, for more accurate predictions, it is necessary to use actual observations of the solar magnetic fields, which are available only for the last four solar cycles. In this paper I briefly discuss the influence of the limited number of available observations on the accuracy of EnKF estimates of solar cycle parameters, the criteria to evaluate the predictions, and application of synoptic magnetograms to the prediction of solar activity. Title: Realistic 3D MHD modeling of self-organized magnetic structuring of the solar corona Authors: Kitiashvili, Irina N.; Wray, Alan A.; Sadykov, Viacheslav; Kosovichev, Alexander G.; Mansour, Nagi N. Bibcode: 2020IAUS..354..346K Altcode: The dynamics of solar magnetoconvection spans a wide range of spatial and temporal scales and extends from the interior to the corona. Using 3D radiative MHD simulations, we investigate the complex interactions that drive various phenomena observed on the solar surface, in the low atmosphere, and in the corona. We present results of our recent simulations of coronal dynamics driven by underlying magnetoconvection and atmospheric processes, using the 3D radiative MHD code StellarBox (Wray et al. 2018). In particular, we focus on the evolution of thermodynamic properties and energy exchange across the different layers from the solar interior to the corona. Title: 3D Modeling of the Structure and Dynamics of a Main-Sequence F-type Star Authors: Kitiashvili, Irina N.; Wray, Alan A. Bibcode: 2020IAUS..354...86K Altcode: 2021arXiv210712575K Current state-of-the-art computational modeling makes it possible to build realistic models of stellar convection zones and atmospheres that take into account chemical composition, radiative effects, ionization, and turbulence. The standard 1D mixing-length-based evolutionary models are not able to capture many physical processes of the stellar interior dynamics. Mixing-length models provide an initial approximation of stellar structure that can be used to initialize 3D radiative hydrodynamics simulations which include realistic modeling of turbulence, radiation, and other phenomena. Title: Cluster Analysis of Spectroscopic Line Profiles in IRIS Observations and RMHD Simulations of the Solar Atmosphere Authors: Sadykov, V. M.; Kitiashvili, I.; Kosovichev, A. G. Bibcode: 2019AGUFMSH31E3345S Altcode: Spatially-resolved spectroscopic observations from IRIS satellite, especially when coupled with realistic 3D RMHD simulations, are a powerful tool for analysis of processes in the solar chromosphere and transition region. However, the complexity of spectroscopic data makes comparison of observations and modeling results difficult. In this work, we apply unsupervised clustering algorithms for analysis of observational and synthetic line profiles to find a compact representation of spectroscopic data and classification in terms of physical characteristics of the radiating solar plasma. In particular, we utilize the quiet-Sun observations from IRIS, and for their interpretation compute synthetic line profiles of the chromospheric Mg II h&k 2796 Å & 2803 Å and transition region C II 1334 Å & 1335 Å lines using the realistic 3D RMHD simulations of the quiescent solar atmosphere (using StellarBox and RH1.5 codes). K-Means clustering algorithm is applied separately to the observed or synthetic spectroscopic line profiles, as well as to their statistical moments (intensity maxima, Doppler shifts, line widths etc). The average silhouette width maximization technique for the K-Means algorithm is utilized to obtain optimal numbers of clusters. We discuss applications of the line profile clustering method to 1) visualizations of computational and observational spectroscopic imaging data; 2) understanding of evolutionary trends and behavior patterns; 3) recognition of heating events and shock waves. Title: Solar activity modeling: from subgranular scales to the solar cycles Authors: Kitiashvili, I.; Wray, A. A.; Sadykov, V. M.; Kosovichev, A. G.; Mansour, N. N. Bibcode: 2019AGUFMSH31E3350K Altcode: Dynamical effects of solar magnetoconvection span a wide range spatial and temporal scales that extends from the interior to the corona and from fast turbulent motions to the global-Sun magnetic activity. To study the solar activity on short temporal scales (from minutes to hours), we use 3D radiative MHD simulations that allow us to investigate complex turbulent interactions that drive various phenomena, such as plasma eruptions, spontaneous formation of magnetic structures, funnel-like structures and magnetic loops in the corona, and others. In particular, we focus on multi-scale processes of energy exchange across the different layers, which contribute to the corona heating and eruptive dynamics, as well as interlinks between different layers of the solar interior and atmosphere.

For modeling the global-scale activity we use the data assimilation approach that has demonstrated great potential for building reliable long-term forecasts of solar activity. In particular, it has been shown that the Ensemble Kalman Filter (EnKF) method applied to the Parker-Kleeorin-Ruzmakin dynamo model is capable of predicting solar activity up to one sunspot cycle ahead in time, as well as estimating the properties of the next cycle a few years before it begins. In this presentation, using the available magnetogram data, we discuss development of the methodology and forecast quality criteria (including forecast uncertainties and sources of errors). We demonstrate the influence of observational limitation on the prediction accuracy. We present the EnKF predictions of the upcoming Solar Cycle 25 based on both the sunspot number series and observed magnetic fields, and discuss the uncertainties and potential of the data assimilation approach for modeling and forecasting the solar activity. Title: Long-Term Prediction of Solar Activity Using Magnetogram Data and Ensemble Kalman Filter Authors: Kitiashvili, Irina; Kosovichev, Alexander G. Bibcode: 2019AAS...23440101K Altcode: Solar activity predictions using the data assimilation approach have demonstrated great potential to build reliable long-term forecasts of solar activity. In particular, it has been shown that the Ensemble Kalman Filter (EnKF) method applied to a non-linear dynamo model is capable of predicting solar activity up to one sunspot cycle ahead in time, as well as estimating the properties of the next cycle a few years before it begins. These developments assume an empirical relationship between the mean toroidal magnetic field flux and the sunspot number. Estimated from the sunspot number series, variations of the toroidal field have been used to assimilate the data into the Parker-Kleeorin-Ruzmakin (PKR) dynamo model by applying the EnKF method. The dynamo model describes the evolution of the toroidal and poloidal components of the magnetic field and the magnetic helicity. Full-disk magnetograms provide more accurate and complete input data by constraining both the toroidal and poloidal global field components, but these data are available only for the last four solar cycles. In this presentation, using the available magnetogram data, we discuss development of the methodology and forecast quality criteria (including forecast uncertainties and sources of errors). We demonstrate the influence of limited time series observations on the accuracy of solar activity predictions. We present EnKF predictions of the upcoming Solar Cycle 25 based on both the sunspot number series and observed magnetic fields and discuss the uncertainties and potential of the data assimilation approach. The research is funded by the NSF SHINE program AGS-1622341. Title: 3D Realistic Modeling of Chromospheric and Coronal Heating and Self-Organization Authors: Kitiashvili, Irina; Wray, Alan A.; Kosovichev, Alexander G.; Sadykov, Viacheslav M.; Mansour, Nagi N. Bibcode: 2019AAS...23410615K Altcode: Turbulent magnetoconvection is a primary driver of the dynamics and structure of the solar atmosphere and corona. Realistic high-resolution radiative MHD simulations reveal a complex multiscale structuring and dynamics above the photosphere. We present a detailed study of dynamical links between small-scale magnetic fields generated by local dynamo action and properties of the chromosphere and corona, as well as effects of coherent self-organized magnetic structures. In particular, we discuss formation of coherent structures, eruptive dynamics, and contributions of multi-scale structuring and highly non-linear dynamics to heating of the chromosphere and corona. Title: New Frontiers for Terrestrial-sized to Neptune-sized Exoplanets In the Era of Extremely Large Telescopes Authors: Wang, Ji; Meyer, Michael; Boss, Alan; Close, Laird; Currie, Thayne; Dragomir, Diana; Fortney, Jonathan; Gaidos, Eric; Hasegawa, Yasuhiro; Kitiashvili, Irina; Konopacky, Quinn; Lee, Chien-Hsiu; Lewis, Nikole K.; Liu, Michael; Lupu, Roxana; Mawet, Dimitri; Melis, Carl; Lopez-Morales, Mercedes; Morley, Caroline V.; Packham, Chris; Peretz, Eliad; Skemer, Andy; Ulmer, Mel Bibcode: 2019BAAS...51c.200W Altcode: 2019arXiv190307556W; 2019astro2020T.200W Detecting and characterizing terrestrial- to Neptune-sized planets (1 < R < 4 REarth) around nearby stars holds the key to understanding the diversity of exoplanets and will ultimately address the ubiquitousness of life in the universe. Here we provide an overview of the challenge and promise of success. Title: Cluster analysis of spectroscopic line profiles in RMHD simulations and observations of the solar atmosphere Authors: Sadykov, Viacheslav M.; Kitiashvili, Irina N.; Kosovichev, Alexander G. Bibcode: 2019shin.confE..11S Altcode: Spatially-resolved spectroscopic observations from the IRIS space mission and ground-based telescopes, coupled with realistic 3D RMHD simulations, are a powerful tool for analysis of processes in the solar atmosphere. To better understand the dynamical and thermodynamic properties in the simulation data and their connection to observations, it is essential to determine similarities in the behaviors of the synthesized and observed spectral line profiles. In this work, we utilize realistic 3D RMHD simulations of the solar atmosphere (using the StellarBox and Bifrost codes) and compute synthetic line profiles of photospheric (Fe I 6173A), chromospheric (H-alpha 6563A, Ca II h&k 3969A&3934A, Mg II h&k 2796A&2803A), and transition region (C II 1334A&1335A) lines. Several clustering algorithms (k-Means clustering, Density-based spatial clustering of applications with noise) are applied separately to the profiles of each calculated spectroscopic line, as well as to the multi-line synthetic data. We discuss application of line profile clustering to visualizations of the computational volume, understanding its evolutionary trends and behavior patterns, and inversion (reconstruction) of physical properties of the solar atmosphere from multi-line spectroscopic data. Title: Reconstructing Extreme Space Weather From Planet Hosting Stars Authors: Airapetian, Vladimir; Adibekyan, V.; Ansdell, M.; Alexander, D.; Barklay, T.; Bastian, T.; Boro Saikia, S.; Cohen, O.; Cuntz, M.; Danchi, W.; Davenport, J.; DeNolfo, G.; DeVore, R.; Dong, C. F.; Drake, J. J.; France, K.; Fraschetti, F.; Herbst, K.; Garcia-Sage, K.; Gillon, M.; Glocer, A.; Grenfell, J. L.; Gronoff, G.; Gopalswamy, N.; Guedel, M.; Hartnett, H.; Harutyunyan, H.; Hinkel, N. R.; Jensen, A. G.; Jin, M.; Johnstone, C.; Kahler, S.; Kalas, P.; Kane, S. R.; Kay, C.; Kitiashvili, I. N.; Kochukhov, O.; Kondrashov, D.; Lazio, J.; Leake, J.; Li, G.; Linsky, J.; Lueftinger, T.; Lynch, B.; Lyra, W.; Mandell, A. M.; Mandt, K. E.; Maehara, H.; Miesch, M. S.; Mickaelian, A. M.; Mouschou, S.; Notsu, Y.; Ofman, L.; Oman, L. D.; Osten, R. A.; Oran, R.; Petre, R.; Ramirez, R. M.; Rau, G.; Redfield, S.; Réville, V.; Rugheimer, S.; Scheucher, M.; Schlieder, J. E.; Shibata, K.; Schnittman, J. D.; Soderblom, David; Strugarek, A.; Turner, J. D.; Usmanov, A.; Van Der Holst, B.; Vidotto, A.; Vourlidas, A.; Way, M. J.; Wolk, Scott J.; Zank, G. P.; Zarka, P.; Kopparapu, R.; Babakhanova, S.; Pevtsov, A. A.; Lee, Y.; Henning, W.; Colón, K. D.; Wolf, E. T. Bibcode: 2019BAAS...51c.564A Altcode: 2019astro2020T.564A; 2019arXiv190306853A The goal of this white paper is to identify and describe promising key research goals to aid the theoretical characterization and observational detection of ionizing radiation from quiescent and flaring upper atmospheres of planet hosts as well as properties of stellar coronal mass ejections (CMEs) and stellar energetic particle (SEP) events. Title: Stellar Characterization Necessary to Define Holistic Planetary Habitability Authors: Hinkel, Natalie; Kitiashvili, Irina; Young, Patrick; Youngblood, Allison Bibcode: 2019BAAS...51c.435H Altcode: 2019arXiv190401089H; 2019astro2020T.435H It is a truism that "to know the planet, you must know the star." We discuss important stellar characteristics that require attention in upcoming ground- and space-based missions, such that their processes can be either detangled from that of the planet, correlated with the presence of a planet, or utilized in lieu of direct planetary observations. Title: Application of Synoptic Magnetograms for Prediction of Solar Activity Using Ensemble Kalman Filter Authors: Kitiashvili, Irina N. Bibcode: 2019shin.confE.215K Altcode: Solar activity predictions using the data assimilation approach have demonstrated great potential to build reliable long-term forecasts of solar activity. In particular, it has been shown that the Ensemble Kalman Filter (EnKF) method applied to a non-linear dynamo model is capable of predicting solar activity up to one sunspot cycle ahead in time, as well as estimating the properties of the next cycle a few years before it begins. These developments assume an empirical relationship between the mean toroidal magnetic field flux and the sunspot number. Estimated from the sunspot number series, variations of the toroidal field have been used to assimilate the data into the Parker-Kleeorin-Ruzmakin (PKR) dynamo model by applying the EnKF method. The dynamo model describes the evolution of the toroidal and poloidal components of the magnetic field and the magnetic helicity. Full-disk magnetograms provide more accurate and complete input data by constraining both the toroidal and poloidal global field components, but these data are available only for the last four solar cycles. In this presentation, using the available magnetogram data, we discuss development of the methodology and forecast quality criteria (including forecast uncertainties and sources of errors). We demonstrate the influence of limited time series observations on the accuracy of solar activity predictions. We present EnKF predictions of the upcoming Solar Cycle 25 based on both the sunspot number series and observed magnetic fields and discuss the uncertainties and potential of the data assimilation approach. Title: Constraining Stellar Photospheres as an Essential Step for Transmission Spectroscopy of Small Exoplanets Authors: Rackham, Benjamin; Pinhas, Arazi; Apai, Dániel; Haywood, Raphaëlle; Cegla, Heather; Espinoza, Néstor; Teske, Johanna; Gully-Santiago, Michael; Rau, Gioia; Morris, Brett M.; Angerhausen, Daniel; Barclay, Thomas; Carone, Ludmila; Cauley, P. Wilson; de Wit, Julien; Domagal-Goldman, Shawn; Dong, Chuanfei; Dragomir, Diana; Giampapa, Mark S.; Hasegawa, Yasuhiro; Hinkel, Natalie R.; Hu, Renyu; Jordán, Andrés; Kitiashvili, Irina; Kreidberg, Laura; Lisse, Carey; Llama, Joe; López-Morales, Mercedes; Mennesson, Bertrand; Molaverdikhani, Karan; Osip, David J.; Quintana, Elisa V. Bibcode: 2019BAAS...51c.328R Altcode: 2019astro2020T.328R; 2019arXiv190306152R Transmission spectra probe the atmospheres of transiting exoplanets, but these observations are also subject to signals introduced by magnetic active regions on host stars. We outline scientific opportunities in the next decade for providing useful constraints on stellar photospheres for the purposes of exoplanet transmission spectroscopy. Title: The Need for Laboratory Measurements and Ab Initio Studies to Aid Understanding of Exoplanetary Atmospheres Authors: Fortney, Jonathan; Robinson, Tyler D.; Domagal-Goldman, Shawn; Genio, Anthony D. Del; Gordon, Iouli E.; Gharib-Nezhad, Ehsan; Lewis, Nikole; Sousa-Silva, Clara; Airapetian, Vladimir; Drouin, Brian; Hargreaves, Robert J.; Huang, Xinchuan; Karman, Tijs; Ramirez, Ramses M.; Rieker, Gregory B.; Tennyson, Jonathan; Wordsworth, Robin; Yurchenko, Sergei N.; Johnson, Alexandria V.; Lee, Timothy J.; Marley, Mark S.; Dong, Chuanfei; Kane, Stephen; López-Morales, Mercedes; Fauchez, Thomas; Lee, Timothy; Sung, Keeyoon; Haghighipour, Nader; Horst, Sarah; Gao, Peter; Kao, Der-you; Dressing, Courtney; Lupu, Roxana; Savin, Daniel Wolf; Fleury, Benjamin; Venot, Olivia; Ascenzi, Daniela; Milam, Stefanie; Linnartz, Harold; Gudipati, Murthy; Gronoff, Guillaume; Salama, Farid; Gavilan, Lisseth; Bouwman, Jordy; Turbet, Martin; Benilan, Yves; Henderson, Bryana; Batalha, Natalie; Jensen-Clem, Rebecca; Lyons, Timothy; Freedman, Richard; Schwieterman, Edward; Goyal, Jayesh; Mancini, Luigi; Irwin, Patrick; Desert, Jean-Michel; Molaverdikhani, Karan; Gizis, John; Taylor, Jake; Lothringer, Joshua; Pierrehumbert, Raymond; Zellem, Robert; Batalha, Natasha; Rugheimer, Sarah; Lustig-Yaeger, Jacob; Hu, Renyu; Kempton, Eliza; Arney, Giada; Line, Mike; Alam, Munazza; Moses, Julianne; Iro, Nicolas; Kreidberg, Laura; Blecic, Jasmina; Louden, Tom; Mollière, Paul; Stevenson, Kevin; Swain, Mark; Bott, Kimberly; Madhusudhan, Nikku; Krissansen-Totton, Joshua; Deming, Drake; Kitiashvili, Irina; Shkolnik, Evgenya; Rustamkulov, Zafar; Rogers, Leslie; Close, Laird Bibcode: 2019astro2020T.146F Altcode: 2019arXiv190507064F We are now in the new era of the characterization of exoplanet atmospheres. However, atmosphere models are often limited by insufficiencies in the laboratory and theoretical data that serve as critical inputs. Here we provide descriptions of areas where new investigations could fill critical gaps in our ability to model exoplanet atmospheres. Title: Statistical Properties of Soft X-Ray Emission of Solar Flares Authors: Sadykov, Viacheslav M.; Kosovichev, Alexander G.; Kitiashvili, Irina N.; Frolov, Alexander Bibcode: 2019ApJ...874...19S Altcode: 2018arXiv181005610S We present a statistical analysis of properties of Soft X-Ray (SXR) emission, plasma temperature (T), and emission measure (EM), derived from Geostationary Operational Environmental Satellite observations of flares in 2002-2017. The temperature and EMs are obtained using the Temperature and EM-based Background Subtraction algorithm, which delivers reliable results together with uncertainties even for weak B-class flare events. More than 96% of flares demonstrate a sequential appearance of T, SXR, and EM maxima, in agreement with the expected behavior of the chromospheric evaporation process. The relative number of such flares increases with increasing the SXR flux maximum. The SXR maximum is closer in time to the T maximum for B-class flares than for ≥C-class flares, while it is very close to the EM maximum for M- and X-class flares. We define flares as “T-controlled” if the time interval between the SXR and T maxima is at least two times shorter than the interval between the EM and SXR maxima, and as “EM-controlled” if the time interval between the EM and SXR maxima is at least two times shorter than the interval between the SXR and T maxima. For any considered flare class range, the T-controlled events compared to EM-controlled events have: (a) higher EM but lower T; (b) longer durations and shorter relative growth times; and (c) longer FWHM and characteristic decay times. Interpretation of these statistical results based on analysis of a single loop dynamics suggests that for flares of the same class range, the T-controlled events can be developed in longer loops than the EM-controlled events. Title: The Origin of Deep Acoustic Sources Associated with Solar Magnetic Structures Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A.; Sandstrom, T. A. Bibcode: 2019ApJ...872...34K Altcode: 2018arXiv181006133K It is generally accepted that solar acoustic (p) modes are excited by near-surface turbulent motions, in particular by downdrafts and interacting vortices in intergranular lanes. Recent analysis of Solar Dynamics Observatory data by Zhao et al. (2015) revealed fast-moving waves around sunspots, which are consistent with magnetoacoustic waves excited approximately 5 Mm beneath the sunspot. We analyzed 3D radiative MHD simulations of solar magnetoconvection with a self-organized pore-like magnetic structure, and identified more than 600 individual acoustic events both inside and outside this structure. By performing a case-by-case study, we found that acoustic sources surrounding the magnetic structure are associated with downdrafts. Their depth correlates with downdraft speed and magnetic field strength. The sources often can be transported into deeper layers by downdrafts. The wave front shape, in the case of a strong or inclined downdraft, can be stretched along the downdraft. Inside the magnetic structure, excitation of acoustic waves is driven by converging flows. Frequently, strong converging plasma streams hit the structure boundaries, causing compressions in its interior that excite acoustic waves. Analysis of the depth distribution of acoustic events shows the strongest concentration at 0.2-1 Mm beneath the surface for the outside sources and mostly below 1 Mm inside the magnetic region, that is, deeper than their counterparts outside the magnetic region. Title: Realistic Radiative 3D MHD Modeling of Outer Convection Zones and Atmospheres of Moderate-Mass Stars Authors: Kitiashvili, Irina Bibcode: 2019atp..prop..132K Altcode: Scientific Goals and Objectives: The primary scientific goal of the proposed study is to understand and characterize the internal structure and turbulent dynamics of the outer convection zones, photospheres, and chromospheres of moderate-mass main-sequence stars using advanced 3D radiative MHD models that are built from first physical principles and take into account the effects of radiation, metallicity, turbulence, and magnetic fields. The primary objectives are: 1) investigate the structural, dynamic, energetic, and turbulent properties of the outer convection zones and atmospheres, including convective overshooting, effects of magnetic fields, and metallicity in solar-type stars; 2) investigate the process of excitation of stellar oscillations and their interaction with turbulent convection and magnetic fields, and 3) generate series of synthetic stellar spectra to link the 3D models with observations. The proposed methodology is based on high-resolution 3D radiative MHD simulations for several stars over the spectral range from F to A with masses from 1.4 to 2 M_Sun by using the StellarBox code, which was specially developed for modeling stellar turbulent convection and atmospheres with a high degree of realism. The computational domain will include layers from the upper radiative zone, through the whole convection zone, and into the low atmosphere. We will investigate the effects of background magnetic fields of various strength and fields spontaneously generated by local dynamo processes. The proposed approach to stellar magnetoconvection modeling is based on first physical principles where the initial conditions for each selected target star are calculated by the stellar evolution code MESA. The synthetic spectral data will be generated from the output of the 3D simulations using available radiative transfer codes: the SPECTRUM code to calculate broad-band spectra of stars, and the SPINOR code for high-resolution spectra of LTE lines. Perceived significance of the proposed work to the objectives of the solicitation and to NASA interests and programs: The proposed study is important and very timely because it will provide a solid background for interpretation of currently available observations from the Kepler, K2 and TESS missions and will provide theoretical support to achieve the mission goals and increase their scientific output. The improved methodologies for characterizing the internal dynamic properties of stars and their surfaces are also important for exoplanet detection, because they provide estimates of stellar noise and radial velocity jitter . The proposed study addresses NASA s Strategic goal: expand the frontiers of knowledge, capability, and opportunity in space ; and NASA s Strategic Objective: Discover how the universe works, explore how it began and evolved, and search for life on planets around other stars . Title: Physics-Based Approach to Predict the Solar Activity Cycles Authors: Kitiashvili, Irina N. Bibcode: 2018shin.confE.155K Altcode: Observations of the complex highly non-linear dynamics of global turbulent flows and magnetic fields are currently available only from Earth-side observations. Recent progress in helioseismology has provided us some additional information about the subsurface dynamics, but its relation to the magnetic field evolution is not yet understood. These limitations cause uncertainties that are difficult take into account, and perform proper calibration of dynamo models. The current dynamo models have also uncertainties due to the complicated turbulent physics of magnetic field generation, transport and dissipation. Because of the uncertainties in both observations and theory, the data assimilation approach is natural way for the solar cycle prediction and estimating uncertainties of this prediction. The data assimilation approach combining information from both models and observations together with estimation possible errors has been developed in a large number of different methodologies. In this presentation I will compare results from four such methodologies: the Ensemble Kalman Filter method, the Extended Kalman Filter, the Ensemble Kalman Filter Smoother, and the Ensemble Adjustment Kalman Filter, for predicting sunspot cycles using a low-order solar dynamo model that takes into account the effects of magnetic helicity balance. I will discuss the prediction results for the upcoming Solar Cycle 25 and their uncertainties. Title: Dynamics of Self-Formed Funnel Structure in 3D Realistic Simulations of a Quiet-Sun Region Authors: Kitiashvili, Irina; Wray, Alan A.; Kosovichev, Alexander G.; Mansour, Nagi Nicolas Bibcode: 2018tess.conf10629K Altcode: Dynamical interaction of the solar convection zone dynamics, chromosphere and corona is challenging in both observational and modeling aspects. Because of complex multi-scale interactions of turbulent MHD flows and structures realistic 3D radiative MHD numerical simulations are needed to shed light on self-organization processes of the turbulent magnetic fields, and investigate physical properties of the solar plasma and dynamical coupling across the layers from the subphotosphere to the corona. We present 3D MHD realistic simulations of the quiet-Sun dynamics, which covers upper layers of the convection zone to 10Mm above the photosphere. The simulations reveal a spontaneous formation of a self-organized funnel-like structure that extends through the chromosphere and corona. We will present thermodynamical properties of the structure, its influence on the dynamics of surrounding areas of the chromosphere and corona, discuss the formation mechanism, and compare the simulation results with IRIS, Hinode and SDO observations. Title: Effects of Distributed Magnetic Fields and Compact Magnetic Structures on Properties of Acoustic Waves Excitation on the Sun Authors: Kitiashvili, Irina; Kosovichev, Alexander G.; Wray, Alan A.; Mansour, Nagi Nicolas Bibcode: 2018tess.conf11504K Altcode: Recent helioseismology interferences have shown possibility of acoustic waves excitation in the subsurface layers much deeper than 200 km. Using 3D radiative MHD numerical simulations, we investigate acoustic wave excitation in the case of distributed magnetic field and spontaneously formed highly magnetized pore-like structures, and show that in the presence of strong magnetic field structures acoustic waves can be excited much deeper than in the quiet-Sun regions. The distribution of acoustic events with depth depends on the magnetic field scale. In particular, in the case of small-scale magnetic patches the acoustic events are located in a relative shallow, 1.5 Mm deep layer, while the acoustic sources located inside of a self-organized pore-like magnetic structure can be found up to 3-4Mm below the surface. We discuss the excitation mechanism, and present an explanation of recent helioseismology observations of deep acoustic sources in sunspots. Title: Using Data Assimilation Methods for Physics-Based Capabilities to Predict Solar Activity Cycles Authors: Kitiashvili, Irina Bibcode: 2018tess.conf31603K Altcode: Difficulties of building reliable forecasts of the strength and duration of solar activity cycles are associated with numerous problems from both observations and dynamo models. Utilization of the mathematical data assimilation approach, in which a theoretical model is 'trained' by observational data, allows us to improve the model solution according to available observations in an optimal way by taking into uncertainties in both observations and model. The data assimilation approach covers a large number of different methods, as well as their parameters that may affect predictive capabilities. In this presentation I will compare application of four data assimilation methodologies: Ensemble Kalman Filter method, Extended Kalman Filter, Ensemble Kalman Filter Smoother and Ensemble Adjustment Kalman Filter for predicting the sunspot cycles using a low-order solar dynamo that takes into account effects of the magnetic helicity balance, and discuss the prediction results for the next solar cycle. Title: Advances in Realistic MHD Simulations of the Sun and Stars Authors: Kitiashvili, Irina N. Bibcode: 2018vsss.book...63K Altcode: No abstract at ADS Title: Realistic Simulations of Stellar Radiative MHD Authors: Wary, Alan A.; Bensassiy, Khalil; Kitiashvili, Irina N.; Mansour, Nagi N.; Kosovichev, Alexander G. Bibcode: 2018vsss.book...39W Altcode: No abstract at ADS Title: 3D Realistic Radiative Hydrodynamic Modeling of a Moderate-Mass Star: Effects of Rotation Authors: Kitiashvili, Irina; Kosovichev, Alexander G.; Mansour, Nagi N.; Wray, Alan A. Bibcode: 2018AAS...23133404K Altcode: Recent progress in stellar observations opens new perspectives in understanding stellar evolution and structure. However, complex interactions in the turbulent radiating plasma together with effects of magnetic fields and rotation make inferences of stellar properties uncertain. The standard 1D mixing-length-based evolutionary models are not able to capture many physical processes of stellar interior dynamics, but they provide an initial approximation of the stellar structure that can be used to initialize 3D time-dependent radiative hydrodynamics simulations, based on first physical principles, that take into account the effects of turbulence, radiation, and others. In this presentation we will show simulation results from a 3D realistic modeling of an F-type main-sequence star with mass 1.47 Msun, in which the computational domain includes the upper layers of the radiation zone, the entire convection zone, and the photosphere. The simulation results provide new insight into the formation and properties of the convective overshoot region, the dynamics of the near-surface, highly turbulent layer, the structure and dynamics of granulation, and the excitation of acoustic and gravity oscillations. We will discuss the thermodynamic structure, oscillations, and effects of rotation on the dynamics of the star across these layers. Title: Solar activity across the scales: from small-scale quiet-Sun dynamics to magnetic activity cycles Authors: Kitiashvili, I.; Collins, N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2017AGUFMSH13A2466K Altcode: Observations as well as numerical and theoretical models show that solar dynamics is characterized by complicated interactions and energy exchanges among different temporal and spatial scales. It reveals magnetic self-organization processes from the smallest scale magnetized vortex tubes to the global activity variation known as the solar cycle. To understand these multiscale processes and their relationships, we use a two-fold approach: 1) realistic 3D radiative MHD simulations of local dynamics together with high-resolution observations by IRIS, Hinode, and SDO; and 2) modeling of solar activity cycles by using simplified MHD dynamo models and mathematical data assimilation techniques. We present recent results of this approach, including the interpretation of observational results from NASA heliophysics missions and predictive capabilities. In particular, we discuss the links between small-scale dynamo processes in the convection zone and atmospheric dynamics, as well as an early prediction of Solar Cycle 25. Title: Data Assimilation and Uncertainties in Early Solar Cycle Predictions Authors: Kitiashvili, Irina Bibcode: 2017SPD....4830602K Altcode: Stochastic nature of solar activity variations together with our limited knowledge of the dynamo mechanism and subsurface dynamics causes uncertainty in predictions of the solar cycle. For improving the physics-based predictions we can take advantage of the mathematical data assimilation approach that allows us to take into account both, observational errors and model uncertainties, and provide estimates of the next solar cycle along with prediction uncertainties. In this study we use the Parker's migratory dynamo model together with the equation of magnetic helicity balance, which reproduces main properties of the sunspot cycles and allow us to minimize discrepancies between the observed global activity variations and the model solution. The test simulation runs show that a reliable prediction can be obtained for two phases of preceding solar cycle: 1) if the polar field reversals shortly after the solar maxima (strong toroidal field and weak poloidal field), and 2) during the solar minima (strongest poloidal and weak toroidal fields). The early estimate of Cycle 25 obtained by this method shows that this cycle will start in 2019 - 2020, reach the maximum in 2023 - 2024, and that the mean sunspot number at the maximum will be about 90 (for the v2.0 sunspot number series). Title: Realistic Modeling of Interaction of Quiet-Sun Magnetic Fields with the Chromosphere Authors: Kitiashvili, Irina; Kosovichev, Alexander G.; Mansour, Nagi N.; Wray, Alan A. Bibcode: 2017SPD....4810502K Altcode: High-resolution observations and 3D MHD simulations reveal intense interaction between the convection zone dynamics and the solar atmosphere on subarcsecond scales. To investigate processes of the dynamical coupling and energy exchange between the subsurface layers and the chromosphere we perform 3D radiative MHD modeling for a computational domain that includes the upper convection zone and the chromosphere, and investigate the structure and dynamics for different intensity of the photospheric magnetic flux. For comparison with observations, the simulation models have been used to calculate synthetic Stokes profiles of various spectral lines. The results show intense energy exchange through small-scale magnetized vortex tubes rooted below the photosphere, which provide extra heating of the chromosphere, initiate shock waves, and small-scale eruptions. Title: Realistic 3D radiative modeling of turbulent structure of moderate-mass stars and Sun Authors: Kitiashvili, Irina N.; Kosovichev, Alexander G.; Wray, Alan A.; Mansour, Nagi N. Bibcode: 2017shin.confE..60K Altcode: Understanding the turbulent dynamics of the Sun and stars is a critical element for interpreting observed processes and phenomena on different scales and for predicting extreme events such as flares and superflares. High-resolution observations of the Sun and high-fidelity radiative MHD numerical simulations have substantially advanced our understanding of solar and stellar local dynamics and magnetism from the upper convection zone to the atmosphere and corona. However, global modeling of the Sun with such a high degree of realism is currently not affordable due to the extremely high computational cost of resolving the scales in the convection zone. The physics of the deep solar dynamics can be effectively addressed through modeling more massive solar-type stars where the convection zone is shallower and the convective overturning time is much shorter than those on the Sun. We present recent 3D realistic simulation results of moderate-mass stars and discuss links between solar and stellar dynamics, such as the multiscale structure of granulation, convective overshoot, and others. In particular, these simulations have provided better understanding of the dynamics of the tachocline (the overshoot layer at the bottom of the convection zone) and have explained long-standing results from helioseismology. Title: Using Data Assimilation Methods for Prediction of Solar Activity Authors: Kitiashvili, Irina N.; Collins, Nancy S. Bibcode: 2017shin.confE..59K Altcode: The variability of solar magnetic activity known as the 11-year solar cycles has the longest history of observations. These solar cycles dramatically affect conditions in the heliosphere and the Earth's space environment. Our current understanding of the physical processes that make up global solar dynamics and the dynamo that generates the magnetic fields is sketchy, resulting in unrealistic descriptions in theoretical and numerical models of the solar cycles. The absence of long-term observations of solar interior dynamics and photospheric magnetic fields hinders development of accurate dynamo models and their calibration. In such situations, mathematical data assimilation methods provide an optimal approach for combining the available observational data and their uncertainties with theoretical models in order to estimate the state of the solar dynamo and predict future cycles. In this presentation, we will discuss the implementation and performance of an Ensemble Kalman Filter data assimilation method based on the Parker migratory dynamo model complemented by the equation of magnetic helicity conservation and long-term sunspot data series. This approach has allowed us to reproduce the general properties of the solar cycles and has already demonstrated a good predictive capability for the current cycle, 24. We will discuss further development of this approach, which includes a more sophisticated dynamo model, synoptic magnetogram data, and employs the DART Data Assimilation Research Testbed. Title: Magnetoacoustic Waves Excitation in Self-Organized Solar Magnetic Structures Authors: Kitiashvili, I.; Kosovichev, A. G.; Mansour, N. N.; Sandstrom, T. A.; Wray, A. A. Bibcode: 2016AGUFMSH21E2570K Altcode: Interaction of the turbulent plasma and magnetic fields is of great interest as a key to understanding self-organization processes and dynamics of the solar magnetism. We develop 3D time-dependent radiative MHD simulations that are based on first principles and provide an important tool for uncovering the basic physical mechanisms. Our simulations are able to reproduce many observed phenomena, and, in particular, allow us to investigate spontaneous formation of coherent highly magnetized flux-robe structures that are observed as "pores" in the photosphere. The dynamical evolution of these structures is accompanied by numerous magnetoacoustic waves that are excited in subphotospheric layers and propagate into the solar atmosphere. We present analysis of the pore dynamics, and properties and excitation mechanism of the magnetoacoustic waves, as well as a comparison with observations. Title: Data Assimilation Approach for Forecast of Solar Activity Cycles Authors: Kitiashvili, Irina N. Bibcode: 2016ApJ...831...15K Altcode: Numerous attempts to predict future solar cycles are mostly based on empirical relations derived from observations of previous cycles, and they yield a wide range of predicted strengths and durations of the cycles. Results obtained with current dynamo models also deviate strongly from each other, thus raising questions about criteria to quantify the reliability of such predictions. The primary difficulties in modeling future solar activity are shortcomings of both the dynamo models and observations that do not allow us to determine the current and past states of the global solar magnetic structure and its dynamics. Data assimilation is a relatively new approach to develop physics-based predictions and estimate their uncertainties in situations where the physical properties of a system are not well-known. This paper presents an application of the ensemble Kalman filter method for modeling and prediction of solar cycles through use of a low-order nonlinear dynamo model that includes the essential physics and can describe general properties of the sunspot cycles. Despite the simplicity of this model, the data assimilation approach provides reasonable estimates for the strengths of future solar cycles. In particular, the prediction of Cycle 24 calculated and published in 2008 is so far holding up quite well. In this paper, I will present my first attempt to predict Cycle 25 using the data assimilation approach, and discuss the uncertainties of that prediction. Title: 3D Realistic MHD Modeling of Solar Activity in Quiet-Sun Regions Authors: Kitiashvili, Irina N.; Kosovichev, Alexander G.; Mansour, Nagi N.; Wray, Alan A. Bibcode: 2016shin.confE.149K Altcode: Despite on the absence of strong highly-energetic events in quiet-Sun regions the amount of energy flux into the chromosphere and corona, generated by small-scale events, makes these areas of great interest to address problems of coronal heating as well as solar wind acceleration. The quiet-Sun regions represent an evolving background state in which the turbulent MHD environment affects properties of sunspots formed from magnetic fluxes emerging from the deep convection, formation of filaments, coronal loops etc. We present recent 3D radiative MHD numerical studies of magnetic self-organization processes driven by the turbulent magnetoconvection in quiet-Sun regions, such as small-scale dynamo and plasma eruptions, and discuss their physical nature, links to high-resolution observations by modeling synthetic spectro-polarimetric data, and also potential impacts on the energetics and dynamics of the corona and inner heliosphere. Title: Early Solar Cycle Prediction with the Data Assimilation Approach: Uncertainties and Future Challenges Authors: Kitiashvili, Irina N. Bibcode: 2016shin.confE..27K Altcode: Solar variability is primarily driven by the evolution of magnetic fields on both local and global scales. Because of the coupled multi-scale nature of the solar magnetism the current dynamo models cannot realistically describe these interactions, limiting our predictive capabilities. An additional limitation lays in our poor knowledge of the structure and dynamics of magnetic fields in the solar convection zone, because observations cover only the solar surface. To overcome these limitations and obtain a more reliable picture of the global evolution of the solar magnetic activity I develop a synergetic analysis that combines of a theoretical dynamo model and observations by applying a data assimilation approach.

Data assimilation is a relatively new approach to develop physics-based predictions and estimate their uncertainties in situations when the physical properties of a system are not well known. Specifically, I will present an application of the Ensemble Kalman Filter method to modeling and prediction of solar cycles by using a low-order non-linear dynamo model, which includes the essential physics and can describe general properties of the sunspot cycles. Despite the simplicity of this model, the data assimilation approach provides reasonable estimates for the strengths of future solar cycles. In particular, the prediction of Cycle 24 calculated and published in 2008 is so far holding quite well. I will present my first attempt to predict the Solar Cycle 25 using the data assimilation approach and will discuss the uncertainties of this prediction. Title: 3D Radiative MHD Modeling of Quiet-Sun Magnetic Activity Authors: Kitiashvili, Irina Bibcode: 2016SPD....47.1205K Altcode: Quiet-Sun regions that cover most of the solar surface represent a background state that plays an extremely important role in the dynamics and energetics of the solar atmosphere. A clear understanding of these regions is required for accurate interpretation of solar activity events such as emergence of magnetic flux, sunspot formation, and eruptive dynamics. Modern high-resolution observations from ground and space telescopes have revealed a complicated dynamics of turbulent magnetoconvection and its effects in the solar atmosphere and corona, showing intense interactions across different temporal and spatial scales. Interpretation of the observed complex phenomena and understanding of their origins is impossible without advanced numerical models. I will present new results of realistic-type 3D radiative MHD simulations of the upper turbulent convective layer and atmosphere of the Sun. The results reveal the mechanism of formation and properties of the Sun’s “magnetic carpet” controlled by subsurface small-scale dynamo processes, and demonstrate interaction between the subsurface layers and the atmosphere via spontaneous small-scale eruptions and wave phenomena. To link the simulations to solar data the spectro-polarimetric radiative transfer code SPINOR is used to convert the simulated data into the Stokes profiles of various spectral lines, including the SDO and Hinode observables. The results provide a detailed physical understanding of the quiet-Sun dynamics, and show potential for future observations with the DKIST and other large solar telescopes. Title: Dynamics of Turbulent Convection and Convective Overshoot in a Moderate-mass Star Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2016ApJ...821L..17K Altcode: 2015arXiv151207298K We present results of realistic three-dimensional (3D) radiative hydrodynamic simulations of the outer layers of a moderate-mass star (1.47 M ⊙), including the full convection zone, the overshoot region, and the top layers of the radiative zone. The simulation results show that the surface granulation has a broad range of scales, from 2 to 12 Mm, and that large granules are organized in well-defined clusters, consisting of several granules. Comparison of the mean structure profiles from 3D simulations with the corresponding one-dimensional (1D) standard stellar model shows an increase of the stellar radius by ∼800 km, as well as significant changes in the thermodynamic structure and turbulent properties of the ionization zones. Convective downdrafts in the intergranular lanes between granulation clusters reach speeds of more than 20 km s-1, penetrate through the whole convection zone, hit the radiative zone, and form an 8 Mm thick overshoot layer. Contrary to semi-empirical overshooting models, our results show that the 3D dynamic overshoot region consists of two layers: a nearly adiabatic extension of the convection zone and a deeper layer of enhanced subadiabatic stratification. This layer is formed because of heating caused by the braking of the overshooting convective plumes. This effect has to be taken into account in stellar modeling and the interpretation of asteroseismology data. In particular, we demonstrate that the deviations of the mean structure of the 3D model from the 1D standard model of the same mass and composition are qualitatively similar to the deviations for the Sun found by helioseismology. Title: 2-D and 3-D models of convective turbulence and oscillations in intermediate-mass main-sequence stars Authors: Guzik, Joyce A.; Morgan, T. H.; Nelson, N. J.; Lovekin, C.; Kosak, K.; Kitiashvili, I. N.; Mansour, N. N.; Kosovichev, A. Bibcode: 2016IAUFM..29B.540G Altcode: 2016arXiv160504455G We present multidimensional modeling of convection and oscillations in main-sequence stars somewhat more massive than the Sun, using three separate approaches: 1) Using the 3-D planar StellarBox radiation hydrodynamics code to model the envelope convection zone and part of the radiative zone. Our goals are to examine the interaction of stellar pulsations with turbulent convection in the envelope, excitation of acoustic modes, and the role of convective overshooting; 2) Applying the spherical 3-D MHD ASH (Anelastic Spherical Harmonics) code to simulate the core convection and radiative zone. Our goal is to determine whether core convection can excite low-frequency gravity modes, and thereby explain the presence of low frequencies for some hybrid γ Dor/δ Sct variables for which the envelope convection zone is too shallow for the convective blocking mechanism to drive gravity modes; 3) Applying the ROTORC 2-D stellar evolution and dynamics code to calculate evolution with a variety of initial rotation rates and extents of core convective overshooting. The nonradial adiabatic pulsation frequencies of these nonspherical models are calculated using the 2-D pulsation code NRO. We present new insights into pulsations of 1-2 M⊙ stars gained by multidimensional modeling. Title: Solar Dynamo on Small and Global Scales Authors: Kitiashvili, I.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2015AGUFMSH23A2432K Altcode: Phenomenon of the solar variability is primarily driven by the evolution of magnetic fields on both small and global scales. Because connection between the dynamo processes on different scales remains unclear, we consider them separately. In particular, we analyze 1) a global dynamo model, which is reduced to a dynamical system in the context of the solar cycle variations, and 2) realistic-type 3D numerical simulations of the small-scale dynamo, and discuss possible interlinks between these dynamo processes. Title: The Sun's Photospheric Convection Spectrum Authors: Hathaway, David H.; Teil, Thibaud; Norton, Aimee A.; Kitiashvili, Irina Bibcode: 2015ApJ...811..105H Altcode: 2015arXiv150803022H Spectra of the cellular photospheric flows are determined from full-disk Doppler velocity observations acquired by the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory spacecraft. Three different analysis methods are used to separately determine spectral coefficients representing the poloidal flows, the toroidal flows, and the radial flows. The amplitudes of these spectral coefficients are constrained by simulated data analyzed with the same procedures as the HMI data. We find that the total velocity spectrum rises smoothly to a peak at a wavenumber of about 120 (wavelength of about 35 Mm), which is typical of supergranules. The spectrum levels off out to wavenumbers of about 400, and then rises again to a peak at a wavenumber of about 3500 (wavelength of about 1200 km), which is typical of granules. The velocity spectrum is dominated by the poloidal flow component (horizontal flows with divergence but no curl) at wavenumbers above 30. The toroidal flow component (horizontal flows with curl but no divergence) dominates at wavenumbers less than 30. The radial flow velocity is only about 3% of the total flow velocity at the lowest wavenumbers, but increases in strength to become about 50% at wavenumbers near 4000. The spectrum compares well with the spectrum of giant cell flows at the lowest wavenumbers and with the spectrum of granulation from a 3D radiative-hydrodynamic simulation at the highest wavenumbers. Title: 2D and 3D Models of Convective Turbulence and Oscillations in Intermediate-Mass Main-Sequence Stars Authors: Guzik, Joyce Ann; Morgan, Taylor H.; Nelson, Nicholas J.; Lovekin, Catherine; Kitiashvili, Irina N.; Mansour, Nagi N.; Kosovichev, Alexander Bibcode: 2015IAUGA..2255601G Altcode: We present multidimensional modeling of convection and oscillations in main-sequence stars somewhat more massive than the sun, using three separate approaches: 1) Applying the spherical 3D MHD ASH (Anelastic Spherical Harmonics) code to simulate the core convection and radiative zone. Our goal is to determine whether core convection can excite low-frequency gravity modes, and thereby explain the presence of low frequencies for some hybrid gamma Dor/delta Sct variables for which the envelope convection zone is too shallow for the convective blocking mechanism to drive g modes; 2) Using the 3D planar ‘StellarBox’ radiation hydrodynamics code to model the envelope convection zone and part of the radiative zone. Our goals are to examine the interaction of stellar pulsations with turbulent convection in the envelope, excitation of acoustic modes, and the role of convective overshooting; 3) Applying the ROTORC 2D stellar evolution and dynamics code to calculate evolution with a variety of initial rotation rates and extents of core convective overshooting. The nonradial adiabatic pulsation frequencies of these nonspherical models will be calculated using the 2D pulsation code NRO of Clement. We will present new insights into gamma Dor and delta Sct pulsations gained by multidimensional modeling compared to 1D model expectations. Title: Radiative 3D MHD simulations of the spontaneous small-scale eruptions in the solar atmosphere Authors: Kitiashvili, Irina N. Bibcode: 2015IAUGA..2258477K Altcode: Studying non-linear turbulent dynamics of the solar atmosphere is important for understanding mechanism of the solar and stellar brightness variations. High-resolution observations of the quiet Sun reveal ubiquitous distributions of high-speed jets, which are transport mass and energy into the solar corona and feeding the solar wind. However, the origin of these eruption events is still unknown. Using 3D realistic MHD numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push the surrounding material up, generating shocks. Our simulations reveal complicated high-speed flow patterns and thermodynamic and magnetic structure in the erupting vortex tubes and shows that the eruptions are initiated in the subsurface layers and are driven by high-pressure gradients in the subphotosphere and photosphere and by the Lorentz force in the higher atmosphere layers. I will discuss about properties of these eruptions, their effects on brightness and spectral variations and comparison with observations. Title: Properties of Turbulent Dynamics and Oscillations of Main-Sequence Stars Deduced From Numerical Simulations Authors: Kitiashvili, Irina N.; Mansour, Nagi N.; Kosovichev, Alexander; Wray, Alan A. Bibcode: 2015IAUGA..2258520K Altcode: Unique observational data from the Kepler mission open new perspectives for detail investigation of dynamical and internal properties of numerous stars. However, the new observational results require better understand links between the stellar turbulent convection and oscillations. We perform 3D numerical radiative hydrodynamics simulations of convective and oscillation properties of main-sequence stars from the solar-type stars to more massive F- and A-type stars. As the stellar mass increases the convection zone shrinks making it possible to include the whole convection zone in the computational domain. Also in more massive stars the scale and intensity of the turbulent motions dramatically increases, providing more energy for excitation of acoustic and gravity modes. In this talk I will discuss properties of the turbulent dynamics of the stars, interaction between the radiative and convection zones, and excitation of acoustic and gravity modes. Title: Scaling properties of turbulent flows on the Sun and stars Authors: Kitiashvili, Irina N. Bibcode: 2015IAUGA..2258535K Altcode: Understanding dynamics of the solar and stellar plasmas is not possible without characterization of turbulent spectral properties by using numerical simulations and observations. Recent progress in observational and computational capabilities allows us to investigate variations of these properties under different physical conditions. I will present analysis of scaling properties of solar and stellar magnetoconvection using results of 3D radiative MHD simulations of the Sun and several main-sequence stars with various masses, and compare with observations. I will discuss a synergy of turbulent scaling properties of convection on different stars and effects of magnetic field. Title: Realistic Modeling of Local Dynamo Processes on the Sun Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2015ApJ...809...84K Altcode: 2015arXiv150608924K Magnetic fields are usually observed in the quiet Sun as small-scale elements that cover the entire solar surface (the “salt-and-pepper” patterns in line-of-sight magnetograms). By using 3D radiative MHD numerical simulations, we find that these fields result from a local dynamo action in the top layers of the convection zone, where extremely weak “seed” magnetic fields (e.g., from a 10-6 G) can locally grow above the mean equipartition field to a stronger than 2000 G field localized in magnetic structures. Our results reveal that the magnetic flux is predominantly generated in regions of small-scale helical downflows. We find that the local dynamo action takes place mostly in a shallow, about 500 km deep, subsurface layer, from which the generated field is transported into the deeper layers by convective downdrafts. We demonstrate that the observed dominance of vertical magnetic fields at the photosphere and horizontal fields above the photosphere can be explained by small-scale magnetic loops produced by the dynamo. Such small-scale loops play an important role in the structure and dynamics of the solar atmosphere and their detection in observations is critical for understanding the local dynamo action on the Sun. Title: Numerical simulations of magnetoconvection and helioseismology Authors: Kitiashvili, I. N. Bibcode: 2015exse.book..238K Altcode: No abstract at ADS Title: Using Realistic MHD Simulations for Modeling and Interpretation of Quiet-Sun Observations with the Solar Dynamics Observatory Helioseismic and Magnetic Imager Authors: Kitiashvili, I. N.; Couvidat, S.; Lagg, A. Bibcode: 2015ApJ...808...59K Altcode: 2014arXiv1407.2663K The solar atmosphere is extremely dynamic, and many important phenomena develop on small scales that are unresolved in observations with the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory. For correct calibration and interpretation of the observations, it is very important to investigate the effects of small-scale structures and dynamics on the HMI observables, such as Doppler shift, continuum intensity, spectral line depth, and width. We use 3D radiative hydrodynamics simulations of the upper turbulent convective layer and the atmosphere of the Sun, and a spectro-polarimetric radiative transfer code to study observational characteristics of the Fe i 6173 Å line observed by HMI in quiet-Sun regions. We use the modeling results to investigate the sensitivity of the line Doppler shift to plasma velocity, and also sensitivities of the line parameters to plasma temperature and density, and determine effective line formation heights for observations of solar regions located at different distances from the disk center. These estimates are important for the interpretation of helioseismology measurements. In addition, we consider various center-to-limb effects, such as convective blueshift, variations of helioseismic travel-times, and the “concave” Sun effect, and show that the simulations can qualitatively reproduce the observed phenomena, indicating that these effects are related to a complex interaction of the solar dynamics and radiative transfer. Title: Simulations of Stellar Magnetoconvection using the Radiative MHD Code `StellarBox' Authors: Wray, Alan A.; Bensassi, Khalil; Kitiashvili, Irina N.; Mansour, Nagi N.; Kosovichev, Alexander G. Bibcode: 2015arXiv150707999W Altcode: Realistic numerical simulations, i.e., those that make minimal use of ad hoc modeling, are essential for understanding the complex turbulent dynamics of the interiors and atmospheres of the Sun and other stars and the basic mechanisms of their magnetic activity and variability. The goal of this paper is to present a detailed description and test results of a compressible radiative MHD code, `StellarBox', specifically developed for simulating the convection zones, surface, and atmospheres of the Sun and moderate-mass stars. The code solves the three-dimensional, fully coupled compressible MHD equations using a fourth-order Padé spatial differentiation scheme and a fourth-order Runge-Kutta scheme for time integration. The radiative transfer equation is solved using the Feautrier method for bi-directional ray tracing and an opacity-binning technique. A specific feature of the code is the implementation of subgrid-scale MHD turbulence models. The data structures are automatically configured, depending on the computational grid and the number of available processors, to achieve good load balancing. We present test results and illustrate the code's capabilities for simulating the granular convection on the Sun and a set of main-sequence stars. The results reveal substantial changes in the near-surface turbulent convection in these stars, which in turn affect properties of the surface magnetic fields. For example, in the solar case initially uniform vertical magnetic fields tend to self-organize into compact (pore-like) magnetic structures, while in more massive stars such structures are not formed and the magnetic field is distributed more-or-less uniformly in the intergranular lanes. Title: Advances in Realistic MHD Simulation Authors: Kitiashvili, I. Bibcode: 2014AGUFMSH31C..03K Altcode: Modern high-resolution observations from ground and space telescopes reveal a complicated dynamics of turbulent magnetoconvection and its effects in the solar atmosphere and corona, showing intense interactions across different temporal and spatial scales. Interpretation of the observed complex phenomena and understanding of their origins is impossible without advanced numerical models. The rapid growth of computational capabilities has made possible 3D radiative MHD numerical simulations that reproduce solar conditions with a high degree of realism. Such simulations allow us to determine physical processes hidden from direct observations. They also provide synthetic data for calibration of observational data and for developing and testing ideas for improved diagnostics. In the talk I will discuss current advances and challenges of modeling multi-scale turbulent magnetoconvection, magnetic self-organization phenomena in the photosphere, their dynamical interaction with the chromospheric layers, and modeling of spectro-polarimetric observations for different instruments. Title: Spectro-polarimetric properties of small-scale plasma eruptions driven by magnetic vortex tubes Authors: Kitiashvili, Irina N. Bibcode: 2014PASJ...66S...8K Altcode: 2014arXiv1407.2295K; 2014PASJ..tmp..112K The highly turbulent nature of convection on the Sun causes strong multi-scale interaction of subsurface layers with the photosphere and chromosphere. According to realistic 3D radiative magnetohydrodynamic numerical simulations, ubiquitous small-scale vortex tubes are generated by turbulent flows below the visible surface and concentrated in the intergranular lanes. The vortex tubes can capture and amplify magnetic field, penetrate into chromospheric layers and initiate quasi-periodic flow eruptions that generate Alfvénic waves, and transport mass and energy into the solar atmosphere. The simulations revealed high-speed flow patterns, and complicated thermodynamic and magnetic structures in the erupting vortex tubes. The spontaneous eruptions are initiated and driven by strong pressure gradients in the near-surface layers, and accelerated by the Lorentz force in the low chromosphere. In this paper, the simulation data are used to further investigate the dynamics of the eruptions, their spectro-polarimetric characteristics for the Fe I 6301.5 and 6302.5 Å spectral lines, and demonstrate expected signatures of the eruptions in the Hinode Spectro-Polarimeter (SP) data. We found that the complex dynamical structure of vortex tubes (downflows in the vortex core and upflows on periphery) can be captured by the Stokes I profiles. During an eruption, the ratio of down and upflows can suddenly change, and this effect can be observed in the Stokes V profile. Also, during the eruption the linear polarization signal increases, and this also can be detected with Hinode SP. Title: Realistic Modeling of Multi-Scale MHD Dynamics of the Solar Atmosphere Authors: Kitiashvili, I.; Mansour, N. N.; Wray, A. A.; Yoon, S.; Kosovichev, A. G. Bibcode: 2014AGUFMSH41B4134K Altcode: Realistic 3D radiative MHD simulations open new perspectives for understanding the turbulent dynamics of the solar surface, its coupling to the atmosphere, and the physical mechanisms of generation and transport of non-thermal energy. Traditionally, plasma eruptions and wave phenomena in the solar atmosphere are modeled by prescribing artificial driving mechanisms using magnetic or gas pressure forces that might arise from magnetic field emergence or reconnection instabilities. In contrast, our 'ab initio' simulations provide a realistic description of solar dynamics naturally driven by solar energy flow. By simulating the upper convection zone and the solar atmosphere, we can investigate in detail the physical processes of turbulent magnetoconvection, generation and amplification of magnetic fields, excitation of MHD waves, and plasma eruptions. We present recent simulation results of the multi-scale dynamics of quiet-Sun regions, and energetic effects in the atmosphere and compare with observations. For the comparisons we calculate synthetic spectro-polarimetric data to model observational data of SDO, Hinode, and New Solar Telescope. Title: Radiative 3D Modeling of Convection of Main-Sequence Stars Authors: Kitiashvili, Irina Bibcode: 2014AAS...22440402K Altcode: Recent progress in observational capabilities, and particularly, the large amount of photometric data from Kepler, require the development of realistic numerical simulations for data interpretation and validation of theoretical models. Current state-of-the-art of computational modeling based on first principles makes it possible to build realistic models of stellar convection zones and atmospheres, which can take into account chemical composition, effects of radiation, ionization and turbulence. I present large-scale 3D time-dependent radiative hydrodynamics simulations for a series of Kepler-target stars with masses from 1.01 Ms to 1.52 Ms and effective temperature varying from 5780 K to 6982 K, and investigate the properties of convection, the surface structure and oscillations. For massive A-type stars, the simulations include the whole outer convection layer and the overshoot region at the interface with the radiative zone. The simulations reveal that in stars that are more massive than the Sun, turbulent convection is highly supersonic and produces multiscale granulation patterns on the surface. These simulation results also show that contrary to current paradigm, turbulent convection plays a very important role in the surface dynamics of A-type stars, and leads to stochastic excitation of acoustic oscillations observed by Kepler. I will also discuss the dynamics of the overshooting region and excitation of internal gravity waves. Title: Realistic Modeling of Spontaneous Flow Eruptions in the Quiet Sun Authors: Kitiashvili, Irina; Yoon, Seokkwan S Bibcode: 2014AAS...22432302K Altcode: Ground and space observations reveal that the solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The origin and driving forces of the observed eruptions are still unknown. Using realistic numerical simulations we find that small-scale plasma eruptions can be produced by ubiquitous magnetized vortex tubes generated in the Sun's turbulent convection. The vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and strengthen the background magnetic field, and push surrounding material up, generating impulses of Alfven waves and shocks. Our simulations reveal complicated high-speed flows, thermodynamic, and magnetic structures in the erupting vortex tubes. We find that the eruptions are initiated in the subsurface layers, and initially are driven by high-pressure gradients in the subphotosphere and photosphere, and are accelerated by the Lorentz force in the higher atmospheric layers. The eruptions are often quasi-periodic with a characteristic period of 2-5 min. These vortex eruptions have a complicated flow helical pattern, with predominantly downward flows in the vortex tube cores and upward flows in their surroundings. For comparison with observations we calculate full Stokes profiles in different wavelength for different space and ground instruments, such as HMI/SDO, Hinode, NST/BBSO, IMaX/Sunrise. In particular, we find that the observed eruption events are not always associated with strong magnetic field concentrations, and that strong field patches can be a source of several simultaneous eruptions. Title: Modeling of SDO/HMI spectro-polarimetric data and center-to-limb variation effects with 3D MHD simulations Authors: Kitiashvili, Irina; Couvidat, Sebastien Bibcode: 2014AAS...22442207K Altcode: Observations with the Solar Dynamics Observatory (SDO), and, in particular, Helioseismic and Magnetic Imager (HMI) provide a unique opportunity to investigate various phenomena simultaneously over the whole solar disk. Current state-of-the-art numerical simulations allow us to model the observational data with a high degree of realism, and use the artificial data for interpretation of observed properties ("observables") in terms of the physical conditions, for the testing of new data analysis techniques and the improvement of data calibration. In the current study we use realistic-type 3D radiative MHD simulations of the upper turbulent convective layer and atmosphere of the Sun, obtained with the SolarBox code, and employ the spectro-polarimetric radiative transfer code SPINOR to convert the simulated data into Stokes profiles of the HMI Fe I 6173 A line for different conditions in the solar atmosphere. For testing the HMI calibration the synthetic Stokes profiles are processed through the SDO/JSOC simplified data analysis pipeline. We investigate properties of the HMI observables for various solar features, variations of the line formation height for different angular distances from the disk center, effects of the spatial resolution and iron abundance, and pay particular attention to the center-to-limb variations effects playing important role in local helioseismology measurements. Title: Multiscale Properties of the Local Dynamo on the Sun Authors: Kitiashvili, Irina; Kosovichev, Alexander G.; Mansour, Nagi N; Wray, Alan A Bibcode: 2014AAS...22410304K Altcode: Dynamics of the quiet Sun represents a background ('salt-and-pepper') state for powerful manifestations of solar activity. Current numerical simulations have shown that small-scale turbulent dynamics can strongly couple with processes on larger scales, such as formation of pores and sunspots. We perform 3D MHD radiative simulations of top layers of the convection zone and the low atmosphere, taking into account effects of turbulence, magnetic fields, ionization and excitation of all abundant elements. To model the dynamo process we carry a series of the simulations with various initial weak levels of magnetic field perturbations. The results show that an initial, randomly distributed ('seed') magnetic field of 1 micro-gauss, greatly amplifies by subsurface turbulent dynamics. The self generated magnetic field (dynamo) reaches 2 kG magnetic levels in the photosphere. The local dynamo process primary operates 1 Mm below the surface where the magnetic fields are amplified by helical flows. These dynamo-generated magnetic fields are transported by downflows into deeper layers. The process of the magnetic field amplification has a substantially multiscale character, during which self-organized turbulent helical flows work coherently on scales much larger then the turbulent scales. We discuss the apparent contradiction of our results with current paradigm that local dynamo can generate magnetic fields only on the small turbulent scales. We compare our results with other simulations and observations. Title: Radiative hydrodynamic simulations of turbulent convection and pulsations of Kepler target stars Authors: Kitiashvili, Irina N. Bibcode: 2014IAUS..301..193K Altcode: The problem of interaction of stellar pulsations with turbulence and radiation in stellar convective envelopes is central to our understanding of excitation mechanisms, oscillation amplitudes and frequency shifts. Realistic (``ab initio'') numerical simulations provide unique insights into the complex physics of pulsation-turbulence-radiation interactions, as well as into the energy transport and dynamics of convection zones, beyond the standard evolutionary theory. 3D radiative hydrodynamics simulations have been performed for several Kepler target stars, from M- to A-class along the main sequence, using a new `StellarBox' code, which takes into account all essential physics and includes subgrid scale turbulence modeling. The results reveal dramatic changes in the convection and pulsation properties among stars of different mass. For relatively massive stars with thin convective envelopes, the simulations allow us to investigate the dynamics the whole envelope convection zone including the overshoot region, and also look at the excitation of internal gravity waves. Physical properties of the turbulent convection and pulsations, and the oscillation spectrum for two of these targets are presented and discussed in this paper. In one of these stars, with mass 1.47 M ⊙, we simulate the whole convective zone and investigate the overshoot region at the boundary with the radiative zone. Title: Mechanism of local dynamo action on the Sun Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2013arXiv1312.0982K Altcode: In the quiet Sun, magnetic fields are usually observed as small-scale magnetic elements, `salt and pepper', covering the entire solar surface. By using 3D radiative MHD numerical simulations we demonstrate that these fields are a result of local dynamo action in the top layers of the convection zone, where extremely weak `seed' magnetic fields can locally grow above the mean equipartition field (e.g., from a $10^{-6}$ G `seed' field to more than 1000 G magnetic structures). We find that the local dynamo action takes place only in a shallow, about 500 km deep, subsurface layer, from which the generated field is transported into deeper layers by convection downdrafts. We demonstrate that the observed dominance of vertical magnetic fields at the photosphere and the horizontal fields above the photosphere can be explained by multi-scale magnetic loops produced by the dynamo. Title: Turbulent Hydrodynamics and Oscillations of Moderate-Mass Stars Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A. Bibcode: 2013ASPC..479..377K Altcode: The solar-type pulsators are characterized by acoustic oscillation modes excited by turbulent convection in the upper convective boundary layer. As the stellar mass increases the convection zone shrinks, the scale and intensity of the turbulent motions increases, providing more energy for excitation of acoustic modes. When the stellar mass reaches about 1.6 solar masses the upper convection zone consists of two very thin layers corresponding to H and He ionization, and in addition to the acoustic modes the stars show strong internal gravity modes. The thin convection zone is often considered insignificant for the stellar dynamics and variability. We use three-dimensional (3D) numerical radiative hydrodynamics simulations to study convective and oscillation properties of Main Sequence stars from the solar-type stars to more massive stars. We present simulation results for some of the target stars selected for the Kepler Guest Observer project “Transition in Variable Stars: From Solar-Type Stars to Gamma-Doradus Stars.” For the moderate-mass (A-type) stars the simulations reveal supersonic granular-type convection of a scale significantly larger than the solar granulation scale, and strong overshooting plumes penetrating into the stable radiative zone, that can affect the oscillation properties of these stars. Title: Mechanisms of formation ofsolar pores and sunspots Authors: Kitiashvili, Irina N. Bibcode: 2013IAUS..294..269K Altcode: Spontaneous formation of self-organized magnetic structures, such as sunspots and pores, is one of intriguing and oldest problems, which represents a complicated interaction of convection and magnetic fields on different scales. Observations of sunspots and pores formation reveal a fast process of accumulation of emerging magnetic field into stable long-living magnetic structures. However, the physical mechanisms of the flux accumulation into the compact magnetic structures with high field strength and their stability are not clear. Development of observational capabilities, theory, and realistic-type MHD numerical simulations open a new level of our understanding of the turbulent processes of the magnetic field accumulation. I discuss the recent progress in observations and radiative MHD simulations that provide important clues for possible mechanisms of formation and stability of sunspots and pores, and their links to the dynamo process. Title: Ubiquitous Solar Eruptions Driven by Magnetized Vortex Tubes Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A. Bibcode: 2013ApJ...770...37K Altcode: 2013arXiv1301.0018K The solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The most prominent of these jets have been known as spicules. However, the mechanism initiating these eruption events is still unknown. Using realistic numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push the surrounding material up, generating shocks. Our simulations reveal complicated high-speed flow patterns and thermodynamic and magnetic structure in the erupting vortex tubes. The main new results are: (1) the eruptions are initiated in the subsurface layers and are driven by high-pressure gradients in the subphotosphere and photosphere and by the Lorentz force in the higher atmosphere layers; (2) the fluctuations in the vortex tubes penetrating into the chromosphere are quasi-periodic with a characteristic period of 2-5 minutes; and (3) the eruptions are highly non-uniform: the flows are predominantly downward in the vortex tube cores and upward in their surroundings; the plasma density and temperature vary significantly across the eruptions. Title: Spin rotation, Chandler wobble and free core nutation of isolated multi-layer pulsars Authors: Gusev, Alexander; Kitiashvili, Irina Bibcode: 2013IAUS..291..392G Altcode: At present time there are investigations of precession and nutation for very different celestial multi-layer bodies: the Earth (Getino 1995), Moon (Gusev 2010), planets of Solar system (Gusev 2010) and pulsars (Link et al. 2007). The long-periodic precession phenomenon was detected for few pulsars: PSR B1828-11, PSR B1557-50, PSR 2217+47, PSR 0531+21, PSR B0833-45, and PSR B1642-03. Stairs, Lyne & Shemar (2000) have found that the arrival-time residuals from PSR B1828-11 vary periodically with a different periods. According to our model, the neutron star has the rigid crust (RC), the fluid outer core (FOC) and the solid inner core (SIC). The model explains generation of four modes in the rotation of the pulsar: two modes of Chandler wobble (CW, ICW) and two modes connecting with free core nutation (FCN, FICN) (Gusev & Kitiashvili 2008). We are propose the explanation for all harmonics of Time of Arrival (TOA) pulses variations as precession of a neutron star owing to differential rotation of RC, FOC and crystal SIC of the pulsar PSR B1828-11: 250, 500, 1000 days. We used canonical method for interpretation TOA variations by Chandler Wobble (CW) and Free Core Nutation (FCN) of pulsar. Title: Using realistic MHD simulations for modeling HMI observables Authors: Kitiashvili, I.; Couvidat, S.; Mansour, N.; Wray, A.; Kosovichev, A. Bibcode: 2013enss.confE.127K Altcode: The solar atmosphere is extremely dynamic, and many important phenomena which develop on small scales are unresolved in the SDO/HMI observations. For correct calibration and interpretation of HMI observations it is very important to investigate the effects of small-scale structures and dynamics on the HMI observables. We use radiative MHD simulations of the upper turbulent convective layer and atmosphere of the Sun and spectro-polarimetric radiative transfer codes to study Stokes profiles of the FeI 6173 line for different conditions in the solar atmosphere, including quiet-Sun regions with various background magnetic field strengths and sunspot umbrae and penumbrae, and discuss effects on HMI observables and interpretation of the HMI data. Title: Investigation of Small-Scale Turbulent MHD Phenomena Using Numerical Simulations and NST Observations Authors: Kitiashvili, I.; Abramenko, V.; Goode, P. R.; Kosovichev, A.; Mansour, N.; Wray, A.; Yurchyshyn, V. Bibcode: 2012IAUSS...6E.104K Altcode: Recent progress in observational capabilities and numerical modeling have provided unique high-resolution information demonstrating complicated dynamics and structures of turbulent flows and magnetic field on the Sun. The realistic approach to numerical simulations is based on physical first principles and takes into account compressible fluid flow in a highly stratified magnetized medium, 3D multi-bin radiative energy transfer between fluid elements, a real-gas equation of state, ionization, and excitation of all abundant species, magnetic effects and sub-grid turbulence. We present new results of 3D radiative MHD simulations of the upper solar convection zone and chromosphere that reveal a fundamental role of small-scale vortex dynamics, and compare the numerical results and predictions with observational results from the 1.6 m clear aperture New Solar Telescope (NST) at Big Bear Observatory. In particular, we investigate formation and dynamics of ubiquitous small-scale vortex tubes mostly concentrated in the intergranular lanes and their role in magnetic structuring and acoustic emission of the Sun. These whirlpool-like flows are characterized by very strong horizontal shear velocities (7 - 11 km/s) and downflows (~7 km/s), and are accompanied by sharp decreases in temperature, density and pressure at the surface. High-speed whirlpool flows can attract and capture other vortices, penetrate into the low chromosphere, and form stable magnetic flux tubes. The simulations also reveal a strong connection between acoustic wave excitation events and the dynamics of vortex tubes. In this talk, we will discuss different aspects of small-scale turbulent dynamics of the low atmosphere from the high-resolution simulations in comparison with recent NST observations, and the strategy for future synergies of numerical simulations and observations with large aperture solar telescopes. Title: 3D MHD Simulations of Spontaneous Flow Ejections by Turbulent Convection into the Chromosphere Authors: Kitiashvili, I.; Kosovichev, A. G.; Mansour, N.; Wray, A. Bibcode: 2012AGUFMSH51A2192K Altcode: Dynamical interaction of the highly turbulent subsurface and the low atmosphere layers is a source of many observed phenomena on various scales in the solar chromosphere. We investigate the energetic and dynamical links between the turbulent convection and the chromosphere by using 3D radiative MHD simulations. Our simulations of quiet-Sun regions reveal ubiquitous formation of small-scale vortex tubes which can drive flow ejections into the chromosphere. The vortex tubes are formed through two basic mechanisms: convective instability inside the granules and the Kelvin-Helmholtz instability in the intergranular lanes. During their formation the vortex tubes become mostly vertical and usually can be detected in the intergranular lanes. Dispute their small scale the vortex tubes represent highly dynamical structures, which can capture surrounding magnetic field and easily penetrate into the atmosphere layers, producing quasi-periodic flow ejections, shocks and Alfven waves, and contribute to the chromosphere heating. Title: Self-organization of the Solar Turbulent Convection in Magnetic Field Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2012ASPC..462..382K Altcode: Observations of the solar surface show a highly turbulent behavior of convection, and reveal coherent structures in distributed magnetic fields. We present results of realistic radiation magneto-hydrodynamics (MHD) simulations in three dimensions (3D) of the solar subsurface layers, and investigate properties of magneto-convection for various magnetic field topologies and strengths. In particular, we discuss the filamentary structure and dynamics of sunspot penumbra, spontaneous formation of pore-like and small-scale magnetic structures, and compare the simulation results with observations. Title: Radiation Hydrodynamics Simulations of Turbulent Convection for Kepler Target Stars Authors: Kitiashvili, I. N.; Guzik, J. A.; Kosovichev, A. G.; Mansour, N. N.; Saio, H.; Shibahashi, H.; Wray, A. A. Bibcode: 2012ASPC..462..378K Altcode: The solar-type pulsators are characterized by acoustic oscillation modes excited by turbulent granular convection in the upper convective boundary layer. As the stellar mass increases the convection zone shrinks, the scale and intensity of the turbulent motions increases, providing more energy for excitation of acoustic modes. When the stellar mass reaches about 1.6 solar masses the upper convection zone consists of two very thin layers corresponding to H and He ionization, and in addition to the acoustic modes the stars show strong internal gravity modes The thin convection zone is often considered insignificant for the stellar dynamics and variability. We use numerical radiation transfer simulations in three dimensions (3D) to study convective and oscillation properties of main-sequence stars from the solar-type stars to more massive stars. In the simulations we used models of the stellar interior, calculated for individual Kepler mission targets. The 3D radiation hydrodynamics simulations reveal supersonic granular-type convection on a scale significantly larger than the solar granulation, and strong overshooting plumes penetrating into the stable radiative zone, which can affect oscillation properties of a star. Title: Detection of Small-scale Granular Structures in the Quiet Sun with the New Solar Telescope Authors: Abramenko, V. I.; Yurchyshyn, V. B.; Goode, P. R.; Kitiashvili, I. N.; Kosovichev, A. G. Bibcode: 2012ApJ...756L..27A Altcode: 2012arXiv1208.4337A Results of a statistical analysis of solar granulation are presented. A data set of 36 images of a quiet-Sun area on the solar disk center was used. The data were obtained with the 1.6 m clear aperture New Solar Telescope at Big Bear Solar Observatory and with a broadband filter centered at the TiO (705.7 nm) spectral line. The very high spatial resolution of the data (diffraction limit of 77 km and pixel scale of 0farcs0375) augmented by the very high image contrast (15.5% ± 0.6%) allowed us to detect for the first time a distinct subpopulation of mini-granular structures. These structures are dominant on spatial scales below 600 km. Their size is distributed as a power law with an index of -1.8 (which is close to the Kolmogorov's -5/3 law) and no predominant scale. The regular granules display a Gaussian (normal) size distribution with a mean diameter of 1050 km. Mini-granular structures contribute significantly to the total granular area. They are predominantly confined to the wide dark lanes between regular granules and often form chains and clusters, but different from magnetic bright points. A multi-fractality test reveals that the structures smaller than 600 km represent a multi-fractal, whereas on larger scales the granulation pattern shows no multi-fractality and can be considered as a Gaussian random field. The origin, properties, and role of the population of mini-granular structures in the solar magnetoconvection are yet to be explored. Title: Fine-scale Magnetic Structures and Flows in Sunspot Simulations Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Wray, A. A.; Mansour, N. N. Bibcode: 2012ASPC..454..253K Altcode: One of most intriguing processes on the Sun is the formation and dynamics of sunspots and active regions, where magneto-convective conditions are very different from quiet Sun regions. High-resolution observations from Hinode and numerical simulations shed light into these processes. In our 3D radiative MHD simulations we take into account real-gas equation of state, ionization and excitation of all abundant spices, turbulent and magnetic effects. We present recent results of numerical simulations of a top layer of the convective zone and the photosphere in the presence of magnetic field of various strength and inclination. The simulation results explain the filamentary organization of penumbra, reveal the mechanisms of the Evershed effect and the sea-serpent behavior of magnetic field lines, and show the subsurface dynamics of umbral dots as a natural consequence of magnetoconvection processes. Title: Vortex tubes of turbulent solar convection Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Lele, S. K.; Wray, A. A. Bibcode: 2012PhyS...86a8403K Altcode: 2011arXiv1112.5925K The investigation of the turbulent properties of solar convection is important for understanding the multi-scale dynamics observed on the solar surface. In particular, recent high-resolution observations have revealed ubiquitous vortical structures, and numerical simulations have demonstrated links between vortex tube dynamics and the magnetic field organization. Simulations have shown the importance of vortex tube interactions in mechanisms of acoustic wave excitation on the Sun. In this paper, we investigate the mechanisms of formation of vortex tubes in highly turbulent convective flows near the solar surface by using realistic radiative hydrodynamic large-eddy simulations. Analysis of data from the simulations indicates two basic processes of vortex tube formation: (i) the development of small-scale convective instability inside convective granules and (ii) a Kelvin-Helmholtz-type instability of shearing flows in intergranular lanes. Our analysis shows that vortex stretching during these processes is a primary source of the generation of small-scale vorticity on the Sun. Title: Simulations and Observational Signatures of Mass Ejections, Alfven Waves and Shocks Driven by Turbulent Magnetized Vortex Tubes Authors: Kitiashvili, Irina N. Bibcode: 2012shin.confE.105K Altcode: The mass and energy supply from the Sun into the solar wind is driven by turbulent convection in the near-surface layers. Therefore, the dynamics of subsurface turbulent processes and their connections to the atmosphere are a key to understanding the energy transport, heating of the atmosphere, corona and wind, and mass eruptions. I present new results of radiative 3D MHD simulations that reveal a fundamental role of small-scale magnetized vortex tubes generated near the solar surface by turbulent convection and penetrating into the higher atmospheric layers, potentially providing the mass and energy for the solar wind in open magnetic field structures.The advanced, realistic type, numerical simulations included most important effects, such as sub-grid scale turbulence, magnetic field, radiation, ionization and excitation of all abundant spices, realistic EOS and initial solar model. The MHD simulations revealed formation of ubiquitous small-scale vortex tubes mostly concentrated in the intergranular lanes, which capture and twist magnetic field lines and penetrate into the high atmospheric layers. This process leads to spontaneous generation of shock and Alfven waves, and is accompanied by small-scale mass ejections. I discuss spectro-polarimetric diagnostics of the vortex tubes and eruptions, and their signatures in recent high-resolution observations. Title: Turbulent Kinetic Energy Spectra of Solar Convection from NST Observations and Realistic MHD Simulations Authors: Kitiashvili, I. N.; Abramenko, V. I.; Goode, P. R.; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A.; Yurchyshyn, V. B. Bibcode: 2012arXiv1206.5300K Altcode: Turbulent properties of the quiet Sun represent the basic state of surface conditions, and a background for various processes of solar activity. Therefore understanding of properties and dynamics of this `basic' state is important for investigation of more complex phenomena, formation and development of observed phenomena in the photosphere and atmosphere. For characterization of the turbulent properties we compare kinetic energy spectra on granular and sub-granular scales obtained from infrared TiO observations with the New Solar Telescope (Big Bear Solar Observatory) and from 3D radiative MHD numerical simulations ('SolarBox' code). We find that the numerical simulations require a high spatial resolution with 10 - 25 km grid-step in order to reproduce the inertial (Kolmogorov) turbulence range. The observational data require an averaging procedure to remove noise and potential instrumental artifacts. The resulting kinetic energy spectra show a good agreement between the simulations and observations, opening new perspectives for detailed joint analysis of more complex turbulent phenomena on the Sun, and possibly on other stars. In addition, using the simulations and observations we investigate effects of background magnetic field, which is concentrated in self-organized complicated structures in intergranular lanes, and find an increase of the small-scale turbulence energy and its decrease at larger scales due to magnetic field effects. Title: Dynamics of Magnetized Vortex Tubes in the Solar Chromosphere Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2012ApJ...751L..21K Altcode: 2012arXiv1201.5442K We use three-dimensional radiative MHD simulations to investigate the formation and dynamics of small-scale (less than 0.5 Mm in diameter) vortex tubes spontaneously generated by turbulent convection in quiet-Sun regions with an initially weak (10 G) mean magnetic field. The results show that the vortex tubes penetrate into the chromosphere and substantially affect the structure and dynamics of the solar atmosphere. The vortex tubes are mostly concentrated in intergranular lanes and are characterized by strong (near sonic) downflows and swirling motions that capture and twist magnetic field lines, forming magnetic flux tubes that expand with height and attain magnetic field strengths ranging from 200 G in the chromosphere to more than 1 kG in the photosphere. We investigate in detail the physical properties of these vortex tubes, including thermodynamic properties, flow dynamics, and kinetic and current helicities, and conclude that magnetized vortex tubes provide an important path for energy and momentum transfer from the convection zone into the chromosphere. Title: Convection-Chromosphere Coupling due to Vortex Tube Dynamic Authors: Kitiashvili, Irina; Kosovichev, A.; Mansour, N.; Wray, A. Bibcode: 2012AAS...22012405K Altcode: Ubiquitous distribution of small-scale vortex tubes on the solar surface was found both in observations and simulations. Complicated dynamics of the turbulent vortex tubes is a source of various observed effects such as acoustic waves excitation and processes of self-organization in magnetized solar plasma. We use realistic-type radiative 3D MHD simulations to investigate in detail different mechanisms of the vortex tube formation by granular flows in the upper convection zone, appearance of vortex tubes on the surface and their interaction with the atmosphere. The simulation results reveal new interesting effects of penetration of the vortex tubes from the turbulent subphotosphere into the chromosphere, interaction between these layers, and influence of the helical motions on thermodynamic properties of the chromosphere. In the presence of background magnetic field, the vortex tubes lead to formation of compact magnetic flux tubes, playing important role in the mass and energy flux into the chromosphere. We discuss implication of the simulation results for future high-resolution observations. Title: Effects of vortex tube dynamics in the chromosphere Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A. Bibcode: 2012decs.confE..96K Altcode: Investigation of the solar atmosphere dynamics cannot be complete without understanding coupling, and mass and energy exchange between the strongly-turbulent subphotosphere and the chromosphere. Modern computational capabilities allow us to construct realistic dynamical models, which take into account dynamical, chemical and radiative properties of the solar plasma. Such simulations based on first physical principles and accurate modeling of effects of magnetic field and small-scale turbulence, coupled with spectro-polarimetric line formation calculations, provide synthetic multi-wavelength observables, and are very important for interpretation of observational data. The simulations allow us to study physical processes and phenomena that have not been resolved in observations. In this talk we will present our recent results of high-resolution 3D radiative MHD numerical simulations of top layers of the convective zone and the chromosphere. The simulations reveal ubiquitous distribution of small-scale swirling motions in quiet-Sun and magnetic regions, forming vortex tubes extending from the subphosphere into the chromosphere. Our results show that these small-scale vortex tubes that originally formed in subsurface layer and penetrate into the chromosphere provide an efficient coupling of the turbulent convective layers with the atmosphere. They play important role in various processes, such as shearing instabilities, wave excitation, formation of magnetic flux tubes and transport of energy, mass, momentum and also turbulent properties from the convection zone into the chromosphere. In the presentation, we will focus on the physical aspects of the vortex tube formation, penetration into the atmosphere, interaction with magnetic fields, their role in the energy exchange, and on observational diagnostics and comparison with observational data. Title: Links between photospheric and chromospheric oscillations Authors: Kosovichev, A. G.; Kitiashvili, I. N.; Mitra-Kraev, U.; Sekii, T. Bibcode: 2012decs.confE..97K Altcode: Oscillations excited by turbulent convection play important in the dynamics and energetics of the solar atmosphere. Oscillations below the acoustic cut-off frequency form photospheric resonant modes trapped in the interior but also penetrating into the chromosphere. Above the frequency cut-off, the oscillations represent traveling waves in the chromosphere that form pseudo-modes due to interference with waves coming from the interior. The physics of the chromospheric oscillations, their coupling to the photospheric oscillations, and their role in the chromospheric dynamics and energetics are not fully understood. The observed oscillation properties strongly depend on the excitation mechanism, interaction with turbulence and radiation, and local structure and dynamics of the chromosphere. Significant advances can be made through multi-wavelength observations of atmospheric oscillations and realistic numerical radiative hydrodynamics simulations. Using Hinode/SOT data we investigate the basic properties of solar oscillations observed at two levels in the solar atmosphere, in the G-band (formed in the photosphere) and in the CaII H line (chromospheric emission). We analyzed the data by calculating the individual power spectra as well as the cross-spectral properties, i.e., coherence and phase shift. The observational properties are compared with theoretical models and numerical simulations. The results reveal significant frequency shifts between the CaII H and G-band spectra, in particular above the acoustic cutoff frequency for pseudo-modes. The cross-spectrum phase shows peaks associated with the acoustic oscillation (p-mode) lines, and begins to increase with frequency around the acoustic cut-off. However, we find no phase shift for the (surface gravity wave) f-mode. The observed properties for the p-modes are qualitatively reproduced in a model that includes a correlated background due to radiative effects. Our results show that multi-wavelength observations of solar oscillations, in combination with radiative hydrodynamics modeling, help to understand the coupling between photospheric and chromospheric oscillations. Title: Vortex tubes of solar convection: formation, properties and dynamics Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A. Bibcode: 2011AGUFMSH43A1927K Altcode: Turbulent convection of the Sun demonstrates very complicated dynamics, which is often associated with different scales of self-organization. In particular, vortex tube structures have been identified initially in numerical simulations and then in high-resolution observations. We present new results of 3D radiative MHD simulations of a top layer of the convective zone that reveal the important role of turbulent vortex tubes in various solar processes: acoustic waves excitation, convective downdrafts, spontaneous formation of stable magnetic structures and others. We consider various aspects of the vortex tubes dynamics, including their formation, identification, physical characteristics, and links to phenomena observed in the quiet Sun and magnetic regions. We compare the simulation results with observational data from SDO/HMI, Hinode and large ground-based telescope. Title: Data Assimilation for Dynamo Modeling and Solar Cycle Prediction Authors: Kitiashvili, I. N. Bibcode: 2011AGUFMSH54A..02K Altcode: Incredible growth of space technologies makes them more and more vulnerable to solar impacts. From this point of view accurate predictions of solar activity on various time scales are critical for planning future space missions, space experiments, and also important for reducing these impacts on ground services. Observed cyclic variations of solar activity are a result of a complicated non-linear dynamo process in the convection zone that is not fully understood. Therefore dynamo models cannot be used for direct predictions. Also, the information about convective flows is usually limited to surface observations, and only recently we have started measurements of interior flows by helioseismology. Data assimilation methods combine the available observational data and models for an efficient and accurate estimation of physical properties of the dynamo process, which cannot be observed directly. This approach allows us to make predictions even when our knowledge of a system is incomplete. It has been successfully used in meteorology, but is relatively new in the solar activity studies. I will discuss the general methodology of data assimilation methods for the solar dynamo modeling, its implementation for short and long term predictions of the sunspot cycles, and also limitations and uncertainties of this approach. Title: Excitation of Solar Acoustic Waves and Vortex Tube Dynamics Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A. Bibcode: 2011sdmi.confE..26K Altcode: Oscillatory behavior is one of the basic properties of the solar surface. Therefore understanding the mechanism of acoustic waves excitation in the turbulent near-surface layer is very important for the interpretation of helioseismology data and development of new methods of helioseismic diagnostics of the solar interior, as well as for understanding of the role of the acoustic flux in the energy transport. Observations of individual impulsive events generating acoustic waves have been mostly detected in the intergranular lanes and are associated with local strong cooling of fluid elements. Also, the modern high-resolution observations revealed a process of dragging of small-scale magnetic concentrations toward the center of a convective vortex motion in the photosphere. A substantial progress is being made from the analysis of high-resolution observational data, particularly from Hinode, Sunrise, NST, and SDO/HMI, and also from high-resolution realistic numerical simulations. The simulations take into account all essential turbulent and other physical properties of the solar plasma, and allow us to look at the scales that cannot be resolved in observations, and also compare the data and models. We present new results of 3D radiative MHD simulations of the upper convection zone and atmosphere, and show that one of the possible mechanisms of the acoustic waves generation is a result of interaction two and more vortex tubes in the intergranular lanes. The process of a vortex annihilation, which produces acoustic waves, the properties of these waves and vortices, magnetic influence on the efficiency of acoustic emission, and comparison with the available observational data will be discussed. Title: Effects of Turbulence Models on Self-Organization Processes in Solar Convection Authors: Wray, A. A.; Mansour, N. N.; Rogachevskii, I.; Kleeorin, N.; Kitiashvili, I. N.; Kosovichev, A. G. Bibcode: 2011sdmi.confE...5W Altcode: Realistic MHD numerical simulations of subsurface flows and magnetic structures have become achievable because of the development of fast supercomputer systems and efficient parallel computer codes. The dynamics of the subsurface layer is particularly critical for understanding the self-organization processes of magnetoconvection on different scales. Realistic simulations of solar convection in the presence of magnetic fields reveal very interesting dynamics and reproduce several phenomena observed in solar active regions. “SolarBox”, a 3-D real-gas radiative MHD code developed at NASA Ames, was used for our simulations. Because both the Reynolds and magnetic Reynolds numbers are extremely high, research into subgrid modeling of MHD in the solar context is essential, and an important feature of this code is the implementation of various subgrid-scale LES turbulence models. We present a comparison of two such models: a Smagorinskii-type subgrid resistivity model and the Turbulent Effective Lorentz Force model (TELF) and discuss the role of LES models for studying the process of magnetic flux tube formation and the turbulent properties of magnetoconvection. Title: Numerical simulations of magnetic structures Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Wray, A. A.; Mansour, N. N. Bibcode: 2011IAUS..273..315K Altcode: We use 3D radiative MHD simulations of the upper turbulent convection layer for investigation of physical mechanisms of formation of magnetic structures on the Sun. The simulations include all essential physical processes, and are based of the LES (Large-Eddy Simulations) approach for describing the sub-grid scale turbulence. The simulation domain covers the top layer of the convection zone and the lower atmosphere. The results reveal a process of spontaneous formation of stable magnetic structures from an initially weak vertical magnetic field, uniformly distributed in the simulation domain. The process starts concentration of magnetic patches at the boundaries of granular cells, which are subsequently merged together into a stable large-scale structure by converging downdrafts below the surface. The resulting structure represents a compact concentration of strong magnetic field, reaching 6 kG in the interior. It has a cluster-like internal structurization, and is maintained by strong downdrafts extending into the deep layers. Title: Realistic MHD simulations of magnetic self-organization in solar plasma Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Wray, A. A.; Mansour, N. N. Bibcode: 2011IAUS..274..120K Altcode: Filamentary structure is a fundamental property of the magnetized solar plasma. Recent high-resolution observations and numerical simulations have revealed close links between the filamentary structures and plasma dynamics in large-scale solar phenomena, such as sunspots and magnetic network. A new emerging paradigm is that the mechanisms of the filamentary structuring and large-scale organization are natural consequences of turbulent magnetoconvection on the Sun. We present results of 3D radiative MHD large-eddy simulations (LES) of magnetic structures in the turbulent convective boundary layer of the Sun. The results show how the initial relatively weak and uniformly distributed magnetic field forms the filamentary structures, which under certain conditions gets organized on larger scales, creating stable long-living magnetic structures. We discuss the physics of magnetic self-organization in the turbulent solar plasma, and compare the simulation results with observations. Title: High-resolution 3D Radiative MHD Simulations Of Turbulent Convection And Spectro-polarimetric Properties Authors: Kitiashvili, Irina; Kosovichev, A. G.; Mansour, N. N.; Stenflo, J. O.; Wray, A. A. Bibcode: 2011SPD....42.1708K Altcode: 2011BAAS..43S.1708K Realistic numerical simulations of solar magnetoconvection play a key role for our understanding of the basic physical phenomena in the subsurface convective boundary layer and the atmosphere. For the accurate modeling of the turbulent processes on the Sun it is important to perform the simulations with the highest possible resolution. Our results have revealed significant changes in properties of the turbulent motions when the resolution is increased. It is particularly interesting that small-scale vortex motions in the intergranular lanes become ubiquitous and strong, and play a critical role in the large-scale organization of the solar dynamics. For the comparison with observational data it is necessary to investigate relationships between the physical and spectro-polarimetric properties in various conditions of the quiet-Sun and magnetic regions, and model the observed parameters. By using the radiative line formation code, SPINOR/STOPRO, we have calculated the Stokes profiles and other characteristics for the spectral line of the Hinode/SOT and SDO/HMI instruments, and compared the simulation results with the observational data. Title: A Mechanism of the Solar Acoustic Emission Authors: Kitiashvili, Irina; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A. Bibcode: 2011SPD....42.1701K Altcode: 2011BAAS..43S.1701K Understanding the mechanism of acoustic waves excitation in the turbulent surface layer is very important for the interpretation of helioseismology data and development of new methods of helioseismic diagnostics of the solar interior, as well as for understanding of the role of the acoustic flux in the energy transport. A substantial progress is being made from the analysis of high-resolution observational data, particularly from Hinode, Sunrise, and SDO/HMI, and also from high-resolution realistic numerical simulations. The simulations take into account all essential turbulent and other physical properties of the solar plasma, and allow us to look at the scales that cannot be resolved in observations, and also compare the data and models. We present new results of 3D radiative hydrodynamics simulations of the upper convection zone and atmosphere, and show that one of the possible mechanisms of the acoustic waves generation is a result of interaction two and more vortex tubes. The process of a vortex annihilation, which produces acoustic waves, the properties of these waves and vortices, and comparison with the available observational data will be discussed. Title: Numerical MHD Simulations of Solar Magnetoconvection and Oscillations in Inclined Magnetic Field Regions Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2011SoPh..268..283K Altcode: 2010SoPh..tmp..239K; 2010arXiv1011.5527K The sunspot penumbra is a transition zone between the strong vertical magnetic field area (sunspot umbra) and the quiet Sun. The penumbra has a fine filamentary structure that is characterized by magnetic field lines inclined toward the surface. Numerical simulations of solar convection in inclined magnetic field regions have provided an explanation of the filamentary structure and the Evershed outflow in the penumbra. In this article, we use radiative MHD simulations to investigate the influence of the magnetic field inclination on the power spectrum of vertical velocity oscillations. The results reveal a strong shift of the resonance mode peaks to higher frequencies in the case of a highly inclined magnetic field. The frequency shift for the inclined field is significantly greater than that in vertical-field regions of similar strength. This is consistent with the behavior of fast MHD waves. Title: LES of turbulent convection in solar-type stars and formation of large-scale magnetic structures Authors: Rogachevskii, I.; Kleeorin, N.; Kitiashvili, I. N.; Kosovichev, A. G.; Wray, A. A.; Mansour, N. N. Bibcode: 2011arXiv1102.1206R Altcode: In this study we investigate the effects of turbulent convection on formation of large-scale inhomogeneous magnetic structures by means of Large-Eddy Simulation (LES) for convection in solar-type stars. The main idea of this study is the implementation of a new subgrid-scale model for the effective Lorentz force in a three-dimensional nonlinear radiative magnetohydrodynamics (MHD) code developed for simulating the upper solar convection zone and lower atmosphere. To this end we derived the energy budget equations, which include the effects of the subgrid-scale turbulence on the Lorentz-force, and implemented the new subgrid-scale turbulence model (TELF-Model) in a three-dimensional nonlinear MHD LES code. Using imposed initial vertical and horizontal uniform magnetic fields in LES with the TELF-Model, we have shown that the magnetic flux tubes formation is started when the initial mean magnetic field is larger than a threshold value (about 100 G). This is in agreement with the theoretical studies by Rogachevskii and Kleeorin (2007). We have determined the vertical profiles of the velocity and magnetic fluctuations, total MHD energy and anisotropy of turbulent magneto-convection, kinetic and current and cross helicities. Title: Excitation of Acoustic Waves by Vortices in the Quiet Sun Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2011ApJ...727L..50K Altcode: 2010arXiv1011.3775K The five-minute oscillations are one of the basic properties of solar convection. Observations show a mixture of a large number of acoustic wave fronts propagating from their sources. We investigate the process of acoustic waves excitation from the point of view of individual events, by using a realistic three-dimensional radiative hydrodynamic simulation of the quiet Sun. The results show that the excitation events are related to the dynamics of vortex tubes (or swirls) in intergranular lanes of solar convection. These whirlpool-like flows are characterized by very strong horizontal velocities (7-11 km s-1) and downflows (≈7 km s-1), and are accompanied by strong decreases of temperature, density, and pressure at the surface and 0.5-1 Mm below the surface. High-speed whirlpool flows can attract and capture other vortices. According to our simulation results the processes of vortex interaction, such as vortex annihilation, can cause excitation of acoustic waves on the Sun. Title: Modeling and Prediction of Solar Cycles Using Data Assimilation Methods Authors: Kitiashvili, Irina N.; Kosovichev, Alexander G. Bibcode: 2011LNP...832..121K Altcode: Variations of solar activity are a result of a complicate dynamo process in the convection zone. We consider this phenomenon in the context of sunspot number variations, which have detailed observational data during the past 23 solar cycles. However, despite the known general properties of the solar cycles a reliable forecast of the 11-year sunspot number is still a problem. The main reasons are imperfect dynamo models and deficiency of the necessary observational data. To solve this problem we propose to use data assimilation methods. These methods combine observational data and models for best possible, efficient and accurate estimates of physical properties that cannot be observed directly. The methods are capable of providing a forecast of the system future state. It is demonstrated that the Ensemble Kalman Filter (EnKF) method can be used to assimilate the sunspot number data into a non-linear α{-}Upomega mean-field dynamo model, which takes into account dynamics of turbulent magnetic helicity. We apply this method for characterization of the solar dynamo properties and for prediction of the sunspot number. Title: Subsurface structure of the Evershed flows in sunspots Authors: Kitiashvili, Irina N.; Kosovichev, Alexander G.; Mansour, Nagi N.; Wray, Alan A. Bibcode: 2011JPhCS.271a2076K Altcode: The radial outflows in sunspot penumbrae, known as the Evershed effect, are of significant interest for understanding the dynamics of sunspots. Local helioseismology has not been able to determine the depth of these flows nor their relationship to mass circulation in sunspots. Recent radiative MHD simulations have provided a convincing explanation of the Evershed flow as a natural consequence of magnetoconvection in the strongly inclined magnetic field region of the penumbra. The simulations reproduce many observational features of penumbra dynamics, including the filamentary structure, the high-speed non-stationary "Evershed clouds", and the "sea-serpent" behavior of magnetic field lines. We present the subsurface structure of the Evershed effect, obtained from numerical simulations, and determine the depth of the radial outflows for various magnetic field strengths and inclinations. The simulations predict that Evershed flows are rather shallow and concentrated in the top 0.5 - 1 Mm layer of the convection zone. This prediction can be tested by local helioseismology methods. Title: Realistic MHD Simulations of Formation of Sunspot-like Structures and Comparison with Observations Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2010AGUFMSH31A1782K Altcode: The process of formation of magnetic structures such as sunspot and pores in the turbulent convection zone is still enigma. However, the recent progress in numerical radiative MHD simulations provides clues about the possible mechanism of magnetic field accumulation in spontaneously formed stable structures. Implementation of sub-grid turbulent models in our "SolarBox" code, gives us the possibility to model more accurately turbulent properties, and reproduce the dynamics of the magnetized plasma. The code takes into account non-ideal (tabular) EOS, effects of ionization, chemical composition, radiation, turbulence and magnetic field. Our simulation results show an important role of vortices, which create local cavity of pressure and are associated with strong converging flows under the surface, during the initial stage of the spontaneous structure formation. The resulting structure represents a compact self-organized concentration of strong magnetic field, reaching ~6 kG in the interior, and ~1.5 kG on the surface. It has a cluster-like internal structurization, and is maintained by strong downdrafts extending into the deep layers. We discuss the role of turbulent MHD dynamics in this mechanism, and compare the simulation results with observations of the sunspot formation process during a magnetic flux emergence, from the Solar Dynamics Observatory and Hinode. Title: Cross-helicity turbulence model: Application to MHD phenomena from solar convection zone to heliosphere Authors: Yokoi, N.; Kitiashvili, I. N.; Kosovichev, A. G. Bibcode: 2010AGUFMSH31A1793Y Altcode: Cross helicity (velocity-magnetic field correlation) is expected to play a key role in several geo/astrophysical processes including dynamo action, suppression of turbulent transport, etc. We discuss the relevance of the cross-helicity effects with the aid of the turbulence model. A turbulence model with the cross-helicity effects incorporated may be called the “cross-helicity turbulence model”. This model is applied to several MHD phenomena ranging from the formations of magnetic fields and plasma motions in the solar convection zone to the solar-wind evolution in the heliosphere. Generation of turbulence quantities depends on the inhomogeneity of large-scale fields, and turbulence in turn determines the configuration of the mean fields through the turbulent transport. Such nonlinear interactions between the mean- and fluctuation-fields are explored with the aid of numerical simulations with cross-helicity turbulence model. Through the comparisons to the observation, validity of the turbulence model is examined. Examinations include (i) A large-eddy simulation of the sunspot flow reveals how and how much cross helicity is generated there; (ii) A eddy-viscosity-type turbulence model shows how the turbulence quantities evolves under the influence of the large-scale velocity and magnetic-field shears. Title: A Precise Asteroseismic Age and Radius for the Evolved Sun-like Star KIC 11026764 Authors: Metcalfe, T. S.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Molenda-Żakowicz, J.; Appourchaux, T.; Chaplin, W. J.; Doǧan, G.; Eggenberger, P.; Bedding, T. R.; Bruntt, H.; Creevey, O. L.; Quirion, P. -O.; Stello, D.; Bonanno, A.; Silva Aguirre, V.; Basu, S.; Esch, L.; Gai, N.; Di Mauro, M. P.; Kosovichev, A. G.; Kitiashvili, I. N.; Suárez, J. C.; Moya, A.; Piau, L.; García, R. A.; Marques, J. P.; Frasca, A.; Biazzo, K.; Sousa, S. G.; Dreizler, S.; Bazot, M.; Karoff, C.; Frandsen, S.; Wilson, P. A.; Brown, T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Campante, T. L.; Fletcher, S. T.; Handberg, R.; Régulo, C.; Salabert, D.; Schou, J.; Verner, G. A.; Ballot, J.; Broomhall, A. -M.; Elsworth, Y.; Hekker, S.; Huber, D.; Mathur, S.; New, R.; Roxburgh, I. W.; Sato, K. H.; White, T. R.; Borucki, W. J.; Koch, D. G.; Jenkins, J. M. Bibcode: 2010ApJ...723.1583M Altcode: 2010arXiv1010.4329M The primary science goal of the Kepler Mission is to provide a census of exoplanets in the solar neighborhood, including the identification and characterization of habitable Earth-like planets. The asteroseismic capabilities of the mission are being used to determine precise radii and ages for the target stars from their solar-like oscillations. Chaplin et al. published observations of three bright G-type stars, which were monitored during the first 33.5 days of science operations. One of these stars, the subgiant KIC 11026764, exhibits a characteristic pattern of oscillation frequencies suggesting that it has evolved significantly. We have derived asteroseismic estimates of the properties of KIC 11026764 from Kepler photometry combined with ground-based spectroscopic data. We present the results of detailed modeling for this star, employing a variety of independent codes and analyses that attempt to match the asteroseismic and spectroscopic constraints simultaneously. We determine both the radius and the age of KIC 11026764 with a precision near 1%, and an accuracy near 2% for the radius and 15% for the age. Continued observations of this star promise to reveal additional oscillation frequencies that will further improve the determination of its fundamental properties. Title: Realistic MHD numerical simulations of solar convection and oscillations in inclined magnetic field regions Authors: Kitiashvili, Irina N.; Kosovichev, Alexander G.; Wray, Alan A.; Mansour, Nagi N. Bibcode: 2010HiA....15..348K Altcode: It is known that physical properties of solar turbulent convection and oscillations strongly depend on magnetic field. In particular, recent observations from SOHO/MDI revealed significant changes of the wave properties in inclined magnetic field regions of sunspots, which affect helioseismic inferences. We use realistic 3D radiative MHD numerical simulations to investigate solar convection and oscillations and their relationship in the presence of inclined magnetic field. In the case of highly inclined and strong 1-1.5 kG field the solar convection develops filamentary structure and high-speed flows (Fig. 1a), which provide an explanation to the Evershed effect in sunspot penumbra (Kitiashvili, et al. 2009). Title: Mechanism of Spontaneous Formation of Stable Magnetic Structures on the Sun Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Wray, A. A.; Mansour, N. N. Bibcode: 2010ApJ...719..307K Altcode: 2010arXiv1004.2288K One of the puzzling features of solar magnetism is formation of long-living compact magnetic structures, such as sunspots and pores, in the highly turbulent upper layer of the solar convective zone. We use realistic radiative three-dimensional MHD simulations to investigate the interaction between magnetic field and turbulent convection. In the simulations, a weak vertical uniform magnetic field is imposed in a region of fully developed granular convection, and the total magnetic flux through the top and bottom boundaries is kept constant. The simulation results reveal a process of spontaneous formation of stable magnetic structures, which may be a key to understanding the magnetic self-organization on the Sun and formation of pores and sunspots. This process consists of two basic steps: (1) formation of small-scale filamentary magnetic structures associated with concentrations of vorticity and whirlpool-type motions, and (2) merging of these structures due to the vortex attraction, caused by converging downdrafts around magnetic concentration below the surface. In the resulting large-scale structure maintained by the converging plasma motions, the magnetic field strength reaches ~1.5 kG at the surface and ~6 kG in the interior, and the surface structure resembles solar pores. The magnetic structure remains stable for the whole simulation run of several hours with no sign of decay. Title: Rotational evolution of planetary systems under the action of gravitational and magnetic perturbations Authors: Kitiashvili, I. N.; Gusev, A. V. Bibcode: 2010CosRe..48..335K Altcode: Dynamics of planets around other stars that demonstrate a variety of possible characteristics is of interest from the point of view of realization of new scenarios of evolution which have not been realized in the Solar System. We consider the rotational evolution of exoplanets under the action of gravitational perturbations and magnetic disturbances using the methods of quality analysis and theory of bifurcation of multiparametric differential equations that describe evolution of non-resonant rotation of a dynamically symmetric planet magnetized along its symmetry axis. We analyze 64 phase portraits describing the evolution of angular momentum vector L for all possible values of planet parameters. The values of parameters are determined for the case when the direct rotation of a planet is changed for its retrograde rotation. Title: Explanation of the Sea-serpent Magnetic Structure of Sunspot Penumbrae Authors: Kitiashvili, I. N.; Bellot Rubio, L. R.; Kosovichev, A. G.; Mansour, N. N.; Sainz Dalda, A.; Wray, A. A. Bibcode: 2010ApJ...716L.181K Altcode: 2010arXiv1003.0049K Recent spectro-polarimetric observations of a sunspot showed the formation of bipolar magnetic patches in the mid-penumbra and their propagation toward the outer penumbral boundary. The observations were interpreted as being caused by sea-serpent magnetic fields near the solar surface. In this Letter, we develop a three-dimensional radiative MHD numerical model to explain the sea-serpent structure and the wave-like behavior of the penumbral magnetic field lines. The simulations reproduce the observed behavior, suggesting that the sea-serpent phenomenon is a consequence of magnetoconvection in a strongly inclined magnetic field. It involves several physical processes: filamentary structurization, high-speed overturning convective motions in strong, almost horizontal magnetic fields with partially frozen field lines, and traveling convective waves. The results demonstrate a correlation of the bipolar magnetic patches with high-speed Evershed downflows in the penumbra. This is the first time that a three-dimensional numerical model of the penumbra results in downward-directed magnetic fields, an essential ingredient of sunspot penumbrae that has eluded explanation until now. Title: Sea-Serpent Magnetic Structure of Sunspot Penumbrae: Observations and MHD Simulations Authors: Kitiashvili, Irina; Bellot Rubio, L. R.; Kosovichev, A. G.; Mansour, N. N.; Sainz Dalda, A.; Wray, A. A. Bibcode: 2010AAS...21631706K Altcode: 2010BAAS...41..899K Recent high-resolution spectro-polarimetric observations of a sunspot detected formation of bipolar magnetic patches in the mid penumbra and propagation of these patches toward the outer penumbral boundary. The observations have been interpreted as an evidence of sea-serpent field lines near the solar surface. Using a radiative 3D MHD code, we model the behavior of solar magnetoconvection in strongly inclined magnetic field of penumbra. The numerical simulation results reproduce the moving bipolar magnetic elements observed in high-resolution SOHO/MDI and Hinode/SOT data and also their physical properties, supporting the sea-serpent model. The simulations explain the sea-serpent structure and dynamics of the penumbral field as a consequence of turbulent magnetoconvection in a highly inclined, strong magnetic field, which forms filamentary structures and has properties of traveling convective wave. The model also shows that the appearance of the sea-serpent magnetic field lines is closely related to high-speed patches ("Evershed clouds") of the penumbra radial outflow. Title: Observations of Emerging Active Regions and Sunspot Formation from SDO/HMI Authors: Kitiashvili, Irina; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A. Bibcode: 2010AAS...21640233K Altcode: Continuous high-resolution data of magnetic fields, Doppler velocity and intensity from the Helioseismic and Magnetic Imager (HMI) on SDO provide an excellent opportunity to investigate the process of formation of sunspots and active regions and compare with theoretical models. We analyze the HMI observations of an emerging active region and formation of sunspots. The results show that the sunspot formation involves accumulation of small-scale magnetic elements into a large-scale magnetic structure and substantial changes of the properties of convection in the region of flux emergence. We discuss the HMI capabilities for studying these processes, and compare the observations with results of numerical MHD simulations. Title: Radiative Hydrodynamic Simulations of Turbulent Convection and Oscillations from Solar-Type to A-Type Stars Authors: Kitiashvili, Irina; Kosovichev, A. G.; Saio, H.; Shibahashi, H.; Wray, A. A.; Mansour, N. N. Bibcode: 2010AAS...21640012K Altcode: 2010BAAS...41..856K We use 3D numerical radiative hydrodynamic simulations to study convective and oscillation properties of main sequence stars from the solar-type stars to more massive stars. The solar-type pulsators are characterized by acoustic oscillation modes excited by turbulent granular convection in the upper convective boundary layer. As the stellar mass increases the convection zone shrinks, the scale and intensity of the turbulent motions increases, providing more energy for excitation of acoustic modes. When the stellar mass reaches about 1.6 solar masses the upper convection zone consists of two very thin layers corresponding to H and He ionization, and in addition to the acoustic modes the stars show strong internal gravity modes The thin convection zone is often considered insignificant for the stellar dynamics and variability. However, the 3D radiative hydrodynamics simulations reveal supersonic granular-type convection of the scale significantly larger than the solar granulation, and strong overshooting plumes penetrating into the stable radiative zone. These plumes may contribute to the excitation of oscillation in A-type stars. Title: The Asteroseismic Potential of Kepler: First Results for Solar-Type Stars Authors: Chaplin, W. J.; Appourchaux, T.; Elsworth, Y.; García, R. A.; Houdek, G.; Karoff, C.; Metcalfe, T. S.; Molenda-Żakowicz, J.; Monteiro, M. J. P. F. G.; Thompson, M. J.; Brown, T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Kjeldsen, H.; Borucki, W. J.; Koch, D.; Jenkins, J. M.; Ballot, J.; Basu, S.; Bazot, M.; Bedding, T. R.; Benomar, O.; Bonanno, A.; Brandão, I. M.; Bruntt, H.; Campante, T. L.; Creevey, O. L.; Di Mauro, M. P.; Doǧan, G.; Dreizler, S.; Eggenberger, P.; Esch, L.; Fletcher, S. T.; Frandsen, S.; Gai, N.; Gaulme, P.; Handberg, R.; Hekker, S.; Howe, R.; Huber, D.; Korzennik, S. G.; Lebrun, J. C.; Leccia, S.; Martic, M.; Mathur, S.; Mosser, B.; New, R.; Quirion, P. -O.; Régulo, C.; Roxburgh, I. W.; Salabert, D.; Schou, J.; Sousa, S. G.; Stello, D.; Verner, G. A.; Arentoft, T.; Barban, C.; Belkacem, K.; Benatti, S.; Biazzo, K.; Boumier, P.; Bradley, P. A.; Broomhall, A. -M.; Buzasi, D. L.; Claudi, R. U.; Cunha, M. S.; D'Antona, F.; Deheuvels, S.; Derekas, A.; García Hernández, A.; Giampapa, M. S.; Goupil, M. J.; Gruberbauer, M.; Guzik, J. A.; Hale, S. J.; Ireland, M. J.; Kiss, L. L.; Kitiashvili, I. N.; Kolenberg, K.; Korhonen, H.; Kosovichev, A. G.; Kupka, F.; Lebreton, Y.; Leroy, B.; Ludwig, H. -G.; Mathis, S.; Michel, E.; Miglio, A.; Montalbán, J.; Moya, A.; Noels, A.; Noyes, R. W.; Pallé, P. L.; Piau, L.; Preston, H. L.; Roca Cortés, T.; Roth, M.; Sato, K. H.; Schmitt, J.; Serenelli, A. M.; Silva Aguirre, V.; Stevens, I. R.; Suárez, J. C.; Suran, M. D.; Trampedach, R.; Turck-Chièze, S.; Uytterhoeven, K.; Ventura, R.; Wilson, P. A. Bibcode: 2010ApJ...713L.169C Altcode: 2010arXiv1001.0506C We present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5 days of science operations, reveal high signal-to-noise solar-like oscillation spectra in all three stars: about 20 modes of oscillation may be clearly distinguished in each star. We discuss the appearance of the oscillation spectra, use the frequencies and frequency separations to provide first results on the radii, masses, and ages of the stars, and comment in the light of these results on prospects for inference on other solar-type stars that Kepler will observe. Title: Prediction of solar activity cycles by assimilating sunspot data into a dynamo model Authors: Kitiashvili, Irina N.; Kosovichev, Alexander G. Bibcode: 2010IAUS..264..202K Altcode: Solar activity is a determining factor for space climate of the Solar system. Thus, predicting the magnetic activity of the Sun is very important. However, our incomplete knowledge about the dynamo processes of generation and transport of magnetic fields inside Sun does not allow us to make an accurate forecast. For predicting the solar cycle properties use the Ensemble Kalman Filter (EnKF) to assimilate the sunspot data into a simple dynamo model. This method takes into account uncertainties of both the dynamo model and the observed sunspot number series. The method has been tested by calculating predictions of the past cycles using the observed annual sunspot numbers only until the start of these cycles, and showed a reasonable agreement between the predicted and actual data. After this, we have calculated a prediction for the upcoming solar cycle 24, and found that it will be approximately 30% weaker than the previous one, confirming some previous expectations. In addition, we have investigated the properties of the dynamo model during the solar minima, and their relationship to the strength of the following solar cycles. The results show that prior the weak cycles, 20 and 23, and the upcoming cycle, 24, the vector-potential of the poloidal component of magnetic field and the magnetic helicity substantial decrease. The decrease of the poloidal field corresponds to the well-known correlation between the polar magnetic field strength at the minimum and the sunspot number at the maximum. However, the correlation between the magnetic helicity and the future cycle strength is new, and should be further investigated. Title: Implementation of Data Assimilation Methods for Dynamo Models to Predict Solar Activity Authors: Kitiashvili, I.; Kosovichev, A. Bibcode: 2009ASPC..416..511K Altcode: Cyclic variations of solar activity are a result of a complicated dynamo process in the convection zone. Despite the regular cyclic variations of solar activity, the chaotic variations of sunspot number from cycle to cycle are difficult to predict. The main reasons are the imperfect dynamo models and deficiency of the necessary observational data. Data assimilation methods iterate observational data and models for possible efficient and accurate estimations of physical properties, which cannot be observed directly. We apply the Ensemble Kalman Filter method for assimilation of the sunspot data into a non-linear mean-field dynamo model, which takes into variations of magnetic helicity and parameters of the solar convection zone from helioseismology. We present the results of application of this data assimilation method for representation of the solar cycles and prediction of variations of the sunspot number, and discuss potentials of data assimilation methods for solar dynamo modeling. Title: The Origin of High-Speed Evershed Flows in Sunspots Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Wray, A. A.; Mansour, N. N. Bibcode: 2009AGUFMSH23B1534K Altcode: Radial outflow of magnetized plasma in sunspot penumbrae, the Evershed effect, has a long history of observations and modeling, since its discovery in 1909. There are several different approaches for explaining this phenomenon, but these models cannot describe various observational facts. We have carried out 3D radiative MHD simulations of solar convection in the presence of magnetic field of different strength and inclination. The simulation results show that when the magnetic field is strong (1-2 kG) and highly inclined towards the surface (by 80-85 degrees) the granular convective cells transform into filamentary, flux-tube like structures with strong horizontal velocities. In addition, the convective process takes the form of traveling waves with convective cells moving in the direction of the field inclination. The combination of these two effects, the filamentary structure and the traveling convective waves, result in high-speed, 4-6 km/s, plasma streams, identified in observations as "Evershed clouds". In the case of a very strong magnetic field the streams form coherent structures across the field. The simulation results reproduce many observed features of the Evershed effect, and allow us to establish links with the previous models. Title: Realistic Numerical Modeling of Solar Magnetoconvection and Oscillations Authors: Kitiashvili, I.; Jacoutot, L.; Kosovichev, A. Bibcode: 2009ASPC..415...83K Altcode: 2009arXiv0901.4369K We have developed 3D, compressible, non-linear radiative MHD simulations to study the influence of magnetic fields of various strengths and geometries on the turbulent convective cells and on the excitation mechanisms of the acoustic oscillations. The results reveal substantial changes of the granulation structure with increased magnetic field, and a frequency-dependent reduction in the oscillation power. These simulation results reproduce the enhanced high-frequency acoustic emission observed at the boundaries of active region (``acoustic halo'' phenomenon). In the presence of inclined magnetic field the solar convection develops filamentary structure with flows concentrated along magnetic filaments, and also exhibits behavior of running magnetoconvective waves, resembling recent observations of the sunspot penumbra dynamics from Hinode/SOT. Title: Numerical Modeling of Solar Convection and Oscillations in Magnetic Regions Authors: Kitiashvili, I. N.; Jacoutot, L.; Kosovichev, A. G.; Wray, A. A.; Mansour, N. N. Bibcode: 2009AIPC.1170..569K Altcode: Solar observations show that the spectra of turbulent convection and oscillations significantly change in magnetic regions, resulting in interesting phenomena, such as high-frequency ``acoustic halos'' around active regions. In addition, recent observations from SOHO/MDI revealed significant changes of the wave properties in inclined magnetic field regions of sunspots, which affect helioseismic inferences. We use realistic 3D radiative MHD numerical simulations to investigate properties of solar convection and excitation and propagation of oscillations in magnetic regions. A new feature of these simulations is implementation of a dynamic sub-grid turbulence model, which allows more accurate description of turbulent dissipation and wave excitation. We present the simulation results for a wide range of the field strength and inclination in the top 6 Mm layer of the convection zone. The results show interesting and unexpected effects in the dynamics and large-scale organization of the magnetoconvection (including traveling waves and shearing flows), and also changes in the excitation properties and spectrum of oscillations, suggesting an explanation of the acoustic ``halos'' observed above the acoustic cut-off frequency. Title: Traveling Waves of Magnetoconvection and the Origin of the Evershed Effect in Sunspots Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Wray, A. A.; Mansour, N. N. Bibcode: 2009ApJ...700L.178K Altcode: 2009arXiv0904.3599K Discovered in 1909, the Evershed effect represents strong mass outflows in sunspot penumbra, where the magnetic field of sunspots is filamentary and almost horizontal. These flows play an important role in sunspots and have been studied in detail using large ground-based and space telescopes, but the basic understanding of its mechanism is still missing. We present results of realistic numerical simulations of the Sun's subsurface dynamics, and argue that the key mechanism of this effect is in nonlinear magnetoconvection that has properties of traveling waves in the presence of a strong, highly inclined magnetic field. The simulations reproduce many observed features of the Evershed effect, including the high-speed "Evershed clouds," the filamentary structure of the flows, and the nonstationary quasiperiodic behavior. The results provide a synergy of previous theoretical models and lead to an interesting prediction of a large-scale organization of the outflows. Title: Realistic 3D MHD Simulations of the Evershed Effect Authors: Kitiashvili, Irina; Kosovichev, A. G.; Wray, A. A.; Mansour, N. N. Bibcode: 2009SPD....40.0906K Altcode: Effect of the horizontal radial outflow in a sunspot penumbra (called "Evershed effect") has a 100-year history of investigations, but its physical nature is not clear yet. The Evershed flows begin at bright penumbral grains and propagate outward along penumbra filaments with the mean velocity of 1 - 2 km/s. High-resolution observations reveal that the Evershed flows are non-stationary, and that the strongest, 4 - 5 km/s, flows appear in quasi-periodic patches, "Evershed clouds". To study the nature of the Evershed effect we simulate behavior of convective motions in the presence strong inclined magnetic field. We use a 3D radiative non-linear MHD code, which describes realistic physical properties: compressible fluid flow in a highly stratified and magnetized plasma, 3D multi-group radiative energy transfer, a real-gas equation of state, and sub-grid scale turbulence models. We present a set of numerical experiments, which include the upper solar convection zone and lower atmosphere for different magnetic field strength (600 - 2000 Gauss) and inclination (0 - 90 degrees). The results show the development of filamentary magnetic structures and systematic flows in the direction of field inclination, strongly resembling the Evershed effect in penumbra. In particular, the simulations reproduce the high-speed "Evershed clouds", relationships between the flow velocity and the field strength and inclination, and other observational characteristics. We discuss the simulation results in the context of previously models, such as the embedded flux tube model, the magnetic gap model and the overturning magnetoconvection model, and argue that the physical mechanism of the Evershed effect is in a non-linear interaction between the narrow overturning convective motions and traveling magnetoconvection waves, formed in highly inclined strong magnetic field regions. Title: Prediction of solar magnetic cycles by a data assimilation method Authors: Kitiashvili, Irina N.; Kosovichev, Alexander G. Bibcode: 2009IAUS..259..235K Altcode: We consider solar magnetic activity in the context of sunspot number variations, as a result of a non-linear oscillatory dynamo process. The apparent chaotic behavior of the 11-year sunspot cycles and undefined errors of observations create uncertainties for predicting the strength and duration of the cycles. Uncertainties in dynamo model parameters create additional difficulties for the forecasting. Modern data assimilation methods allow us to assimilate the observational data into the models for possible efficient and accurate estimations of the physical properties, which cannot be observed directly, such as the internal magnetic fields and helicity. We apply the Ensemble Kalman Filter method to a low-order non-linear dynamo model, which takes into account variations of the turbulent magnetic helicity and reproduces basic characteristics of the solar cycles. We investigate the predictive capabilities of this approach, and present test results for prediction of the previous cycles and a forecast of the next solar cycle 24. Title: Magnetic and tidal interactions in spin evolution of exoplanets Authors: Kitiashvili, Irina N. Bibcode: 2009IAUS..259..303K Altcode: The axis-rotational evolution of exoplanets on close orbits strongly depends on their magnetic and tidal interactions with the parent stars. Impulsive perturbations from a star created by periodical activity may accumulate with time and lead to significant long-term perturbations of the planet spin evolution. I consider the spin evolution for different conditions of gravitational, magnetic and tidal perturbations, orbit eccentricity and different angles between the planetary orbit plane and the reference frame of a parent star. In this report I present a summary of analytical and numerical calculations of the spin evolution, and discuss the problem of the star-planet magnetic interaction. Title: Nonlinear dynamical modeling of solar cycles using dynamo formulation with turbulent magnetic helicity Authors: Kitiashvili, I. N.; Kosovichev, A. G. Bibcode: 2009GApFD.103...53K Altcode: 2008arXiv0807.3192K Variations of the sunspot number are important indicators of the solar activity cycles. The sunspot formation is a result of a dynamo process inside the Sun, which is far from being understood. We use simple dynamical models of the dynamo process to simulate the magnetic field evolution and investigate general properties of the sunspot number variations during the solar cycles. We have found that the classical Parker's model with a standard kinetic helicity quenching cannot represent the typical profiles of the solar-cycle variations of the sunspot number, and also does not give chaotic solutions. For modeling of the solar cycle properties we use a nonlinear dynamo model of Kleeorin and Ruzmaikin (1982), which takes into account dynamics of the turbulent magnetic helicity. We have obtained a series of periodic and chaotic solutions for different layers of the convective zone. The solutions qualitatively reproduce some basic observational features of the solar cycle properties, in particular, the relationship between the growth time and the cycle amplitude. Also, on the longer time scale the dynamo model with the magnetic helicity has intermittent solutions, which may be important for modeling long-term variations of the solar cycles. Title: Using Data Assimilation Methods for Modeling and Predicting Solar Activity Cycles Authors: Kitiashvili, I. N.; Kosovichev, A. G. Bibcode: 2008AGUFMSH13A1506K Altcode: Modern data assimilation methods allow us to adapt a model to observations by estimating the true state of a system and taking into account uncertainties in the data and the model. The Ensemble Kalman Filter (EnKF) method provides an effective data assimilation for models of nonlinear dynamics. It is based on analysis of an ensemble of model solutions. We implement the EnKF method for modeling the 11-year sunspot number variations. Using this approach we propose a new physics-based method for predicting for the strength of the solar sunspot cycles. For the initial modeling of the sunspot number we use a dynamo model of Kleeorin and Ruzmaikin dynamo model in a low-mode approximation. The model includes the Parker's dynamo equations and an equation for conservation of the magnetic helicity. Also, we accept Bracewell's suggestion to relate the toroidal magnetic field, B, to the sunspot number, W,in the form of a three-halfs law: W ~ B3/2. We investigate non-linear solutions of the dynamo model and find periodic and chaotic solutions for the convection zone parameters, which represent basic properties of the solar cycles, such as the mean profile of solar cycle and the relationship between the cycle amplitude and the growth and decay times. By applying the EnKF method to the non-linear periodic solutions we reproduce the annual variations of the sunspot number and investigate the predictive capabilities. For testing we calculate forecasts for the 10 previous cycles and find a reasonable agreement with the observations. The calculations of the forecast of the upcoming solar cycle 24 indicate that this cycle will be weaker than the previous one, with the maximum sunspot number of about 80. This investigation shows that data assimilation methods may be useful for evaluating solar dynamo models and for forecasting solar activity. Title: Application of Data Assimilation Method for Predicting Solar Cycles Authors: Kitiashvili, I.; Kosovichev, A. G. Bibcode: 2008ApJ...688L..49K Altcode: 2008arXiv0807.3284K Despite the known general properties of the solar cycles, a reliable forecast of the 11 yr sunspot number variations is still a problem. The difficulties are caused by the apparent chaotic behavior of the sunspot numbers from cycle to cycle and by the influence of various turbulent dynamo processes, which we are far from understanding. For predicting the solar cycle properties we make an initial attempt to use the Ensemble Kalman Filter (EnKF), a data assimilation method, which takes into account uncertainties of a dynamo model and measurements, and allows us to estimate future observational data. We present the results of forecasting of the solar cycles obtained by the EnKF method in application to a low-mode nonlinear dynamical system modeling the solar α Ω -dynamo process with variable magnetic helicity. Calculations of the predictions for the previous sunspot cycles show a reasonable agreement with the actual data. This forecast model predicts that the next sunspot cycle will be significantly weaker (by ~30%) than the previous cycle, continuing the trend of low solar activity. Title: Inner core wobble and free core nutation of pulsar PSR B1828-11 Authors: Kitiashvili, I.; Gusev, A. Bibcode: 2008AdSpR..42.1391K Altcode: PSR B1828-11 has long-term, highly periodic and correlated variations in pulse shape and a slow-down rate with period variations of approximately 1000, 500 and 250 days [Stairs, I.H., Lyne, A.G., Shemar, S.L. Evidence for free precession in a pulsar. Nature 406, 484-486, 2000]. There are three potential explanations of pulses time-of-arrival from a pulsar. These are related to the interior of the neutron star, planetary bodies, free precession and nutation. We use the Hamiltonian canonical method of Getino (1995) for analyzing the dynamically symmetric pulsar PSR B1828-11, consisting of a rigid crust, elliptical liquid outer core and solid inner core. Using the theory of differential rotation of a pulsar, we investigate the dependence on Chandler wobble period, inner core wobble, retrograde free core nutation and prograde free inner core nutation from ellipticity of the inner crystal core, outer liquid core and total pulsar. Title: Quasi-periodical variations of pulsars spin as mimicry of differential rotation Authors: Kitiashvili, I.; Gusev, A. Bibcode: 2008epsc.conf..507K Altcode: ABSTRACT Observation of pulsars is a powerful source of information for studying the dynamics and internal structure of neutron stars. Known about quasi-periodical fluctuations of the time-of-arrival of radiation(TOA) for some pulsars, which we explain as Chandler wobble, Free core nutation, Free inner core nutation and Inner core wobble in case three layer model. Using hamilton approximation to theory rotation of multilayer celestial bodies we estimate dynamical flattening for different layers for PSR B1828-11. It is known that an innate feature of pulsar radiation is high stability of the time-of-arrival (TOA) of pulses, and therefore the analysis of TOA fluctuations can reflect subtle effects of neutron stars dynamics. TOA variations of pulsars can be interpreted by three reasons: gravitational perturbation of pulsar by planetary bodies, peculiarities of a pulsar interior like Tkachenko oscillations and free precession motion, when axis of rotation do not coincide with vectors of the angular moment of solid crust, liquid outer core and crystal core. The radial velocity of a star is obtained by measuring the magnitude of the Doppler effect in its spectrum. Stars showing a small amplitude variation of the radial velocity can be interpreted as systems having planetary companions. Assuming that the pulsar PSR B1257+12 has a mass of 1:35M¯, the Keplerian orbital radii are 0.9, 1.4 and 2.1 AU and with masses are 3:1M©=sin(i), 10:2M©=sin(i), 4:6M©=sin(i), where i is the orbital inclination [7]. In 2000, Stairs, Lyne and Shemar reported about their discovery of long-term, highly-periodic and correlated variations of pulse shape and the rate of slow-down of the pulsar PSR B182811 with period variations approximately 1000, 500, 250 and 167 days, which may be a result of the spin axis caused by an asymmetry in the shape of the pulsar. The long-periodic precession phenomenon was also detected for a few pulsars: PSR 2217+47, PSR 0531+21, PSR B083345, PSR B182811, PSR B164203 [2,3,6,]. The rotation of the terrestrial planets having rigid mantle, outer liquid and inner solid cores is characterized by Chandler wobble, Inner core wobble, Free Core Nutation, Free Inner Core Nutation. Like the Earth, a neutron star can undergo a free precession [4]. The period of precession is defined by deformation of a pulsar and tension in crust and mantle. If the crust and the core of pulsar have differential rotation then axis of a pulsar rotation will be precess, because axis of deformation will not coincide with axis of rotation. The three-layer model is more complicated than the previous case therefore classical methods fail. Escapa, Getino and Ferrandiz [1] developed a canonical formulation for an three-layer Earth model. We research model of pulsar, which includes three layers (fig. 1): an axis symmetrical rigid mantle, a fluid outer core (FOC) and a solid inner core (SIC). Flattened of the pulsar, it's FOC and SIC are Here A;C;Af ;Cf ;As;Cs;Ac;Cc are moments of inertia of the pulsar, FOC, SIC and total core accordingly; e, ef , ec are the flattening of total pulsar, FOC, core and SIC accordingly. In case rotation of a three-layer neutron star we have variations of next types: the Chandler Wobble (CW) is a motion of the pulsar rotation axis around its dynamical figure due to the bulges of the pulsar (it is the only global rotational mode for completely solid pulsar); the Free Core Nutation (FCN) is a differential rotation of the liquid core relatively the crust rotation; This mode does exist only if the core is liquid; the Free Inner Core Nutation (FICN) is a mode related to the differential rotation of the inner core with respect to the other layers of the pulsar. The mode exists only if the pulsar has two-layer core contains outer liquid and inner solid components; the Inner Core Wobble (ICW) is a differential rotation of the figure axis of the pulsar core with respect to the rotation axis of the pulsar and is due to the flattened of the inner core, having an excess of density with respect to the liquid core. This mode does exist only if there is an ellipsoidal solid inner core inside a liquid core in the pulsar. We propose the explanation for four harmonics of TOA pulses variations as precession of a neutron star owing to differential rotation of crust, outer liquid core and inner crystal core of the pulsar PSR B1828-11. In the frame of the three-layer model we investigate the free rotation of dynamically-symmetrical PSR B1828-11 by Hamilton methods proposed Getino [1]. The model explains generation of four modes in the rotation of the pulsar: two modes of Chandler wobbles (CW, ICW) and two modes connecting with free core nutation (FCN, FICN). The neutron star has rigid the crust, the fluid outer core and the solid inner core. We consider four models of an internal structure of pulsars (tabl. 1) in the frame of three-layer approximation. We are used three models of pulsar (tabl. 1, M1 - M3) for modeling of inner, outer cores flattening and total pulsar. The periods of variations can be described in next way where ± is a small parameter has the analytical expression [6] here Cb f and Ab f are the principal inertia moments corresponding to a spherical layer in the FOC with radius equal to the major semiaxia of the SIC which encloses the solid inner core [1]. The observation of PSR B1828-11 has revealed the existence of four periodic variations TOA pulses. In the frame of the three-layer model we proposed the explanation for all pulse fluctuations by differential rotation crust, outer core and inner core of the neutron star. We received estimations of dynamical flattening of the inner and outer cores for pulsar. We have offered the realistic model of the dynamical pulsar structure and two explanations of the feature of flattened of the crust, the outer core and the inner core of the pulsar. (Kitiashvili and Gusev, 2008) References [1] Escapa, A. et al. (2001), J.Geoph.Res., 106, B6, 11387. [2] Kitiashvili, I. (2004) PhD thesis, Moscow University. [3] Kitiashvili, I.N. and Gusev, A.V. (2008) Astronomy Reports, 52(1), 61. [4] Pines, D. and Shaham J. (1974), Nature, 248, 483. [5] Stairs, I.H. et al. (2000), Nature, 406, 484. [6] Suleymanova, S.A. and Shitov, Y.P. (1994), ApJ.Lett., 422, 17. [7] Wolszczan A. (1997), Celest. & Dyn. Astr., 68, 13. Title: Modeling of evolution of the rotational axis of “hot Jupiter” planets under tidal perturbations Authors: Kitiashvili, Irina Bibcode: 2008IAUS..249..197K Altcode: 2007IAUS..249..197K In this report, we present results of analytical and numerical calculations of evolution the axis of rotation of planets moving at very close orbits. We consider the evolution of the axis of rotation caused by tidal perturbations of a parent star and obtain estimates of the principal moment of inertia and the dynamical flattening for nine exoplanets. From analysis of evolutionary equations, we obtain the critical values of the kinetic momentum vector, $\vec L$, for different values of orbital eccentricity. We find a general tendency of vector $\vec L$ to evolve to the direction perpendicular to the orbital plane. Title: Application of Data Assimilation Methods to Non-Linear Dynamo Models of Solar Cycle Authors: Kitiashvili, I.; Kosovichev, A. Bibcode: 2008AGUSMSP23A..02K Altcode: Solar dynamo is a very complicated non-linear oscillatory MHD process, which is far from understanding. It produces 11-year sunspot cycles, which show chaotic behavior and are hard to predict. It has been suggested that the basic oscillatory behavior of the solar dynamo can be described in terms of simple non-linear dynamical systems. The data assimilation approach developed in meteorology and Earth science makes possible efficient and accurate estimations of physical properties, which cannot be observed directly. The applications of data assimilation to non-linear dynamo models for modeling and predicting the solar cycle are discussed in this presentation. Title: Rotational evolution of exoplanets under the action of gravitational and magnetic perturbations Authors: Kitiashvili, Irina N.; Gusev, Alexander Bibcode: 2008CeMDA.100..121K Altcode: 2008CeMDA.tmp....5K We investigate the evolution of the rotational axes of exoplanets under the action of gravitational and magnetic perturbations. The planet is assumed to be dynamically symmetrical and to be magnetised along its dynamical-symmetry axis. By qualitative methods of the bifurcation theory of multiparametric PDEs, we have derived a gallery of 69 phase portraits. The portraits illustrate evolutionary trajectories of the angular momentum {ěc L} of a planet for a variety of the initial conditions, for different values of the ratio between parameters describing gravitational and magnetic perturbations, and for different rates of the orbital evolution. We provide examples of the phase portraits, that reveal the differences in topology and the evolutionary track of {ěc L} in the vicinity of an equilibrium state. We determine the bifurcation properties, i.e., the way of reorganisation of phase trajectories in the vicinities of equilibria; and we point out the combinations of parameters’ values that permit ip-overs from a prograde to a retrograde spin mode. Title: Application of Data Assimilation Methods to Non-Linear Solar Dynamo Models Authors: Kitiashvili, I. Bibcode: 2008ASPC..383..255K Altcode: Prediction of parameters of the 11-year solar cycles is one the most interesting problems of solar physics, in which helioseismology observations play an important role. However, the knowledge of the underlying processes is incomplete, and this makes predictions of the solar cycles difficult. The data assimilation approach developed in meteorology and Earth science makes possible efficient and accurate estimations of physical properties, which cannot be observed directly. To a first approximation, the solar dynamo models can be described in terms of simple, Lorenz-type, dynamical systems. The application of data assimilation to this type of models and the initial results are discussed in this paper. Title: Long-period variations of pulsar emission and the dynamical ellipticity of neutron stars Authors: Kitiashvili, I. N.; Gusev, A. V. Bibcode: 2008ARep...52...61K Altcode: 2008AZh....85...69K Assuming that the observed periodic variations of pulsar emission are due to the free precession of the spin axis, we investigate the evolution of the rotation of a two-layer neutron star using the Hamiltonian method of Getino. We model the dynamical characteristics of a rotating neutron star using the observed variations of the emission of seven pulsars. We estimate the dependence of the period of the Chandler wobble, the period of precession of the spin axis, and the dynamical ellipticity of a neutron star on the model used to describe the super-dense neutron matter and the mass of the star. Title: Dynamical Flattening of Crust, Fluid Outer Core and Solid Inner Core for PSR B1828-11 Authors: Kitiashvili, I.; Gusev, A. Bibcode: 2006IAUJD...6E..11K Altcode: An investigation of rotation variations allows studying a structure of a neutron star. Analysis of the time-of-arrival (TOA) pulses fluctuations can be reflection of thin effects of neutron stars rotational dynamics. In observations of radiation from some pulsars: PSR 2217+47, PSR 0531+21, PSR B0833-45, PSR B1828-11, PSR B1642-03 a long periodic fluctuations of TOA pulses with period from 25 to 6136 days were detected. PSR B1828-11 has long-term, highly periodic and correlated variations pulse shape and of the rate of slow-down with period variations approximately 1000, 500, 250 and 167 days. TOA variations of pulsars can be interpreted by three reasons: gravitational perturbation by planetary bodies, peculiarities of a pulsar interior like Tkachenko oscillations and free precession motion, when axis of rotation do not coincide with vectors of the angular moment of solid crust, liquid outer core and crystal core. We use the Hamiltonian canonical method of Getino for the dynamically symmetrical three-layer model of the pulsar PSR B1828-11. We explane four harmonics of pulses variations as precessions and nutations of a neutron star owing to differential rotation of crust, fluid outer core (FOC) and solid inner core (SIC) by Chandler wobble (CW), Inner Chandler Wobble (ICW), Free Core Nutation (FCN) and Free Inner Core Nutation (FICN). We have got the estimates of dynamical flattening of the crust, the FOC and the SIC of the pulsar (~10^-9) for known periodic variations of the TOA pulse from PSR B1828-11: P[CW] = 167 days, P[ICW] = 500 days, P[FCN] = 250 days, P[FICN] = 1000 days. With increase of pulsar radius on 1.1 km the dynamical flattening of crust grows in 5.5 times, and flattening of fluid outer core increases only in 1.5 times. Changing of the radius of the inner core (from 0.6 to 1.1 km) almost does not influence to dynamical flattening of the solid inner core. We have estimates the flateness of crust ~ 0.3 · 10^-9, flateness of FOC ~ 0.6 · 10^-9 and flateness of SIC is ~ 4.7 · 10^-9. We have offered the realistic model of the dynamical pulsar structure and two explanations of the feature of flattening of the crust, the outer fluid core and the inner solid core of the pulsar. Title: Normal Modes in Rotation of Two/Three Layers Planets Authors: Gusev, A.; Petrova, N.; Kitiashvili, I. Bibcode: 2006IAUJD..10E..36G Altcode: In many theoretical investigations the normal modes of the linearized equations of rotation are computed, yielding both the periods and the eigenspaces of three librations. The modern view of internal structure of the planet takes into account a complex two- or three-layer model. For a planet with a solid inner core and a liquid outer core, there are four rotational normal modes. This numbers is reduced to two for a planet without inner core, and to one for a planet without liquid core. All types of modes are result of non-coincidence of rotation axes and of the main inertia moments of mantle, outer and inner core. For the Earth and the nearest planets - Mars and Moon - there is a wide spectrum of observations and theoretical speculations about parameters of the planet's deep interior. For instance, the most interesting data on dynamics and internal structure of the Moon are already accumulated as a result of the different observations and space experiments. The Japanese space experiments Lunar A, SELENE-missions, Luna Glob (Russia) planed for 2007 - 2012 years will contribute significantly to the information about the Moon: qualitative parameter Q, Love number k[2], core's radius R[c], core's density etc. In a case of free rotation of the two- or three-layer planet the two or four modes in its polar motion might be observed. The evaluations of the periods were made: periods of the Free Core Nutation (FCN) were obtained for Mercury (P[FCN] = 597 yrs) and first time for Venus (P[FCN] = 1534 yrs). For the Moon the period of Free Inner Core Nutation (FICN) P[FICN]= 515 - 634 yrs and the period of Inner Core Wobble (ICW) P[ICW]= 101 - 108 yrs were computed for different models of the lunar core. The main tendency of behavior of two new periods (P [FICN ]and P[ICW]) is preliminary revealed: a) the FICN-period decreases both with the increasing of the core's radius and of the thick of fluid shell; b) conversely, the ICW-period have the direct ratio to radius of a core and thickness of a liquid layer. Title: Astronomy in the Russian Scientific-Educational Project: "KAZAN-GEONA-2010" Authors: Gusev, A.; Kitiashvili, I. Bibcode: 2006IAUSS...2E..38G Altcode: The European Union promotes the Sixth Framework Programme. One of the goals of the EU Programme is opening national research and training programs. A special role in the history of the Kazan University was played by the great mathematician Nikolai Lobachevsky - the founder of non-Euclidean geometry (1826). Historically, the thousand-year old city of Kazan and the two-hundred-year old Kazan University carry out the role of the scientific, organizational, and cultural educational center of the Volga region. For the continued successful development of educational and scientific-educational activity of the Russian Federation, the Republic Tatarstan, Kazan was offered the national project: the International Center of the Sciences and Internet Technologies "GeoNa" (Geometry of Nature - GeoNa - is wisdom, enthusiasm, pride, grandeur). This is a modern complex of conference halls including the Center for Internet Technologies, a 3D Planetarium - development of the Moon, PhysicsLand, an active museum of natural sciences, an oceanarium, and a training complex "Spheres of Knowledge". Center GeoNa promotes the direct and effective channel of cooperation with scientific centers around the world. GeoNa will host conferences, congresses, fundamental scientific research sessions of the Moon and planets, and scientific-educational actions: presentation of the international scientific programs on lunar research and modern lunar databases. A more intense program of exchange between scientific centers and organizations for a better knowledge and planning of their astronomical curricula and the introduction of the teaching of astronomy are proposed. Center GeoNa will enable scientists and teachers of the Russian universities with advanced achievements in science and information technologies to join together to establish scientific communications with foreign colleagues in the sphere of the high technology and educational projects with world scientific centers. Title: Precession of inner crystal core and free nutation of outer liquid core of a pulsar Authors: Gusev, Alexander; Kitiashvili, Irina Bibcode: 2006GrCo...12...59G Altcode: No abstract at ADS Title: Transition from a direct rotation to the reverse rotation of exoplanets by action of the basic perturbations Authors: Gusev, A.; Kitiashvili, I. Bibcode: 2006epsc.conf..260G Altcode: The discovery of 188 planets, around the main sequence stars and around the pulsars, has attracted considerable interest to the cosmogonical problems connected with the formation and early evolution of planets. The process of planetary formation is significantly determined by the orbital-rotational characteristics of exoplanets. Researches of transition from direct rotation to the reverse rotation of a planet in Solar system by action of tidal interaction have been investigated Beletsky (1995), Laskar et al. (2003). For short-periodic exoplanetary systems a reverse rotation of planets are also possible for a special combination of gravitational, magnetic perturbations and evolutions of an orbital plane without of planetary tidal evolution. We investigated possibilities of transition from direct rotation to reverse rotation of exoplanet by action of gravitational (γ), magnetic (α) perturbations and evolutions of an orbital plane by methods of the qualitative analysis and the theory bifurcations the multipleparameter differential equations. We constructed gallery of phase portraits, which describe rotary evolution exoplanet for a wide range of values of perturbed parameters. We described bifurcation surfaces, which show topological reorganization of phase trajectories in a vicinity of equilibrium states (ES) and selected combination of parameters. In gallery of phase portraits exists two basic types of bifurcations: 1) formation of a topologically complex saddle in result of mixing of two centers and a simple saddle; 2) transition from a complex saddle of ES to the center. The first type of bifurcation will be for transition from a condition |α| < |γ| to |α| = |γ|. Bifurcations of the second type are possible, if a ratio of parameters from |α| = |γ| will pass to |α| > |γ|. If gravitational perturbations are dominant, then on the phase sphere exist three areas: 1. area of reverse rotation of exoplanet; 2. area of direct rotation with an opportunity the realization of regime with periodic change of direct rotation of a planet to reverse rotation; and 3. area libration motion of a vector of kinetic momentum with periodic change of direct rotation to reverse motion. When magnetic field is absent, the trace structure illustrates a precession of the vector of kinetic moment of a planet around the normal to the orbital plane. Phase portraits demonstrate behaviour of the vector of kinetic moment of a planet in dependence on the all possible values of parameters planetary systems. The investigations have support by the grant MK-2736.2005.2 of the President of the Russian Federation for the state support young Russian scientists. Title: Qualitative and bifurcation analysis of gravi-magnetic interactions for the spin-orbit evolution of extra-solar systems Authors: Kitiashvili, I.; Gusev, A. Bibcode: 2006epsc.conf..256K Altcode: Detection of extra-solar planets has expanded ours representations about possibilities for realization of different regimes of planetary dynamics. Now are discovered 188 exoplanets in 146 planetary systems about main sequence stars and 4 planets about pulsars PSR B1257+12 and PSR B1620-26. Among open planetary systems 18 are multiplanetary, into their structure are including 41 exoplanets and 3 brown dwarfs. 1. In connection with a diversity of dynamical characteristics of exoplanets we investigate a spin evolution of planets for a wide spectrum of parameters of gravitational, magnetic perturbations and effects of orbit evolution. Structure of planetary systems depends on the effects of their own rotation. 2. Known, that the Sun and some planets of the Solar system have own magnetic field. The reason of formation coplanar planetary orbits and observable distribution of the moment of motion is the influence of electromagnetic forces at early stages of evolution of Solar system. Magnetization of the central body of planetary system is a necessary condition of formation of planets. We investigate not resonant rotation of the magnetized along an axis of symmetry a dynamically symmetrical exoplanet (A = B) in a magnetic field of a star under action of the gravitational (γ) and magnetic (α) moments, take into consideration also effects of evolution of orbit. Structure of phase portraits and their evolution are described by the following properties: 1. exists two or four states of equilibrium (ES) depending on a ratio of parameters; 2. in result of confluence of two centers and saddle located between them appear a topological saddle or a center; 3. during migration or bifurcation of ES, one of equilibrium states is constant. Separatrixes of saddle break a surface of sphere on three areas containing one center. In result of reduction of γ parameter and increase α, two centers migrate to ES of type "saddle". When γ = α, two centers will merge with transformation ES from a simple saddle to topological complex saddle. When α > γ, the new formed topological saddle will disappear with formation on its place the center. We obtained gallery from 64 phase portraits on a plane and on sphere for all values of parameters of evolutionary system of the equations under action of the basic perturb moments. The analysis of the phase portraits gallery gives a wide spectrum of evolutionary tracks of rotation exoplanets. Variation of gravitational and magnetic fields due to planetary evolution causes displacement and change of ES kind. The investigations have support by the grant MK-2736.2005.2 of the President of the Russian Federation for the state support young Russian scientists. Title: Precession of inner core and free nutation of outer core of pulsar PSR B1828-11 Authors: Kitiashvili, I.; Gusev, A. Bibcode: 2006cosp...36.2037K Altcode: 2006cosp.meet.2037K Observation of pulsars is a powerful source of the information for research of dynamics and internal structure of neutron stars Analysis of the time-of-arrival pulses fluctuations can be reflection of thin effects of neutron stars rotational dynamics The long-periodic precession phenomenon was detected for pulsars PSR 2217 47 PSR 0531 21 PSR B0833-45 PSR B1828-11 PSR B1642-03 with period from 25 to 6136 days PSR B1828-11 has long-term highly periodic and correlated variations pulse shape and of the rate of slow-down with period variations approximately 1000 500 250 and 167 days We explane for all harmonics of pulses variations as precession of a neutron star owing to differential rotation of crust outer liquid core and inner crystal core of the pulsar We use the Hamiltonian canonical method of Getino for the dynamically symmetrical three-layer model of the pulsar PSR B1828-11 We investigated dependence flateness of crust outer and inner cores of pulsar from periods Chandler wobble Inner Chandler Wobble Free Core Nutation and Free Inner Core Nutation from ellipticity of inner crystal core outer liquid core and total pulsar We have estimates the flateness of crust and outer core are sim 1 8 10 -11 and flateness of inner core is sim 1 5 10 -8 Title: The Moon in the Russian scientific-educational project: Kazan-GeoNa-2010 Authors: Gusev, A.; Kitiashvili, I.; Petrova, N. Bibcode: 2006cosp...36.2040G Altcode: 2006cosp.meet.2040G Historically thousand-year Kazan city and the two-hundred-year Kazan university Russia carry out a role of the scientific-organizational and cultural-educational center of Volga region For the further successful development of educational and scientific-educational activity of the Russian Federation the Republic Tatarstan Kazan is offered the national project - the International Center of the Science and the Internet of Technologies bf GeoNa bf Geo metry of bf Na ture - bf GeoNa is developed - wisdom enthusiasm pride grandeur which includes a modern complex of conference halls up to 4 thousand places the Center the Internet of Technologies 3D Planetarium - development of the Moon PhysicsLand an active museum of natural sciences an oceanarium training a complex Spheres of Knowledge botanical and landscape oases In center bf GeoNa will be hosted conferences congresses fundamental scientific researches of the Moon scientific-educational actions presentation of the international scientific programs on lunar research modern lunar databases exhibition Hi-tech of the equipment the extensive cultural-educational tourist and cognitive programs Center bf GeoNa will enable scientists and teachers of the Russian universities to join to advanced achievements of a science information technologies to establish scientific communications with foreign colleagues in sphere of the high technology and educational projects with world space centers Title: Chandler Wobble and Free Core Nutation of Neutron Stars Authors: Gusev, A.; Kitiashvili, I. Bibcode: 2004IAUS..218...45G Altcode: Extending the theory of core-mantle differential rotation of a planet, we have obtained the periods PCW and PFCN for different pulsars in the second approximation. We have investigated the dependence of these periods on the equation of state of neutron liquid, flatness of mantle and crust of the neutron star. Title: Early evolution of the planetary system around PSR B1257+12 Authors: Gusev, Alexander; Kitiashvili, Irina Bibcode: 2004IAUS..202..187G Altcode: No abstract at ADS Title: Extra-solar planets: from direct rotation into reverse rotation Authors: Kitiashvili, Irina; Gusev, Alexander Bibcode: 2004IAUS..202..205K Altcode: No abstract at ADS Title: Inner chandler wobble and free core nutation of pulsar Authors: Gusev, A.; Kitiashvili, I. Bibcode: 2004cosp...35.3301G Altcode: 2004cosp.meet.3301G PSR B1828-11 have long-term, highly periodic and correlated variations pulse shape and of the rate of slow-down with period variations approximately 1000, 500 and 250 days (Stairs et al., 2000). There are three potential explanations of time of arrival pulses from pulsar concerned with the interior of the neutron star, planetary bodies and free precession and nutation. The rotation of the terrestrial planets having rigid mantle, outer liquid and inner crystal cores are characterized by Chandler Wobble (CW), Inner Chandler Wobble (ICW), Free Core Nutation (FCN), Free Inner Core Nutation (FICN). We use the Hamiltonian canonical technique of Getino (1997) for dynamically symmetrical pulsar composed of the rigid crust, elliptical liquid mantle and crystal core. Correctly extending theory of core-mantle-crust differential rotation of a body, we have obtained the periods of PCW, PICW, PFCN and PFICN for different pulsars. We investigated dependence of period CW and FCN from the state equation of neutron liquid, flatness of mantle and crust of the neutron star. Detection the CW, ICW, FCN and FICN of the pulsar and its periods allow: to determine crust, mantle and core radiuses and it's flattening; to determine density jump at the Crust-Mantle Boundary and Core-Mantle Boundary. Title: Research of protoplanetary disks of the young pulsars Authors: Kitiashvili, I.; Gusev, A. Bibcode: 2004cosp...35.3290K Altcode: 2004cosp.meet.3290K At present time is known approximately 750 radiopulsars, from them 27 pulsars is observed in other bands and only seven are observed in the optical band. Discovery exoplanets around PSR B1257+12 and PSR B1828-11 gave strong push for search and investigation of planets around neutron stars. At the early stages of planet evolution the tidal and magnetic interactions of exoplanet with disk takes a principal role: the tidal effects lead to the capture into resonance rotation of the planet, the analyses of gravi-magnetic interaction has shown that a direct rotation of the planet may be passed into reverse rotation and vice versa for a rather broad range of the parameters. The dynamical structure of protoplanetary disk are reviewed. Investigation of protoplanetary disk around the optic pulsar by VLTI for combination of observed periodic delays in the arrival times of pulsar pulses are proposed. Measurements of the near-IR sizes of the central regions of the young neutron stars, with high-resolution interferometric studies of protoplanetary disks should help clarify how disk structure affects formation and migration of exoplanet. Title: Orbital resonances in exoplanetary systems Authors: Gusev, A.; Kitiashvili, I. Bibcode: 2003EAEJA.....8390G Altcode: Now opening of 88 planetary systems, that include 104 planets: 101 are Jupiter's type near main sequence stars and 3 are terrestrial type near pulsar, has generated huge interest to fundamental questions of cosmogony, to formation and early evolution of Earth-type planets, stability of planetary systems in the extreme conditions, influence gravitational, magnetic fields and tidal effects on formation of resonant structures in the universe. Among all extra-solar planets 41 exoplanets are short-periodic (before 180 days), 35 are middle-periodic and 28 long-periodic (more 1000 days) planets with the revolution periods P are varied from 2.99 days (HD 83443) to 5360 days (55 Cnc); planetary masses therewith lie in the range 0.015 M⊕ (PSR 1257+12) and 11 MJ; the main semi-axes a lie between 0.038 AU (HD 83443) and 5.9 AU (55 Cnc), eccentricity of the planets varies from 0.0 (15 planets) to 0.927 in HD80606; inclination for five planetary systems are 85.20 for HD 209458, 460 for ɛ Eridani, 250 for 55 Cnc, 370 for Gliese 876, 84.30 for BD -10 3166; six planets Ups And, Gl 777A, HD 114783, HR810, HD 27442, HD 28185 circulate in habitable zone a ∼ 0.5 - 3 AU, P ∼ 240 - 500 days, e < 0.2. From known multiplanetary systems we can see class of planetary systems with resonances: HD 82943 (2:1), Gliese 876 (2:1), 55 Cnc (3:1), PSR 1257+12 (2:3), 47 Uma (3:7), HD 12661 (2:11). At the early stages of planet evolution the tidal and magnetic interactions takes a principal role - the tidal effects lead to the capture into resonance rotation of the planet, while the gravi-magnetic interaction shows that a direct rotation of the planet may be passed into reverse rotation and vice versa for a rather broad range of the parameters. We investigate the equations describing the evolution of the kinetic momentum vector for dynamically symmetrical planets by action of gravitational, magnetic and tidal interaction with the central star. The obtained gallery of more twenty phase portraits of kinetic momentum evolution illustrates the various regimes of the planetary systems evolution. Title: Exoplanets around pulsars Authors: Kitiashvili, I.; Gusev, A. Bibcode: 2003EAEJA.....6227K Altcode: Surprise discovery of thrid planets and cometary body (!?) near the pulsar PSR~B1257+12 (Wolszczan and Frail, 1992) posed the problems of describing their moving around pulsar, their origin and early rotation. At the present time the question whether there exist another three pulsars in the planetary systems is under discussion: PSR 0329+54 (1 planet), PSR B1620--26 (1 planet) and PSR 1828--11 (3 planets, Stairs et al., 2000) . It is known the time scale of pulsars is very stable, then in some cases the periodical fluctuation in time of arrival may be provoked motion of planetary bodies, free precession or concerned with the interior of the neutron star. Discovery exoplanets around PSR~B1257+12 gave strong push for search and investigate planets around neutron stars. Dust disks around stars still retain information about the formation processes of the exoplanetary systems as they are formed by collisions of planetesimals or protoplanets.The conventional explanation for the formation gas giant planets, core accretion, presumes that a gaseous envelope collapses upon a roughly 10 M⊕, solid core that was formed by the collisional accumulation of planetary embryos orbiting in a gaseous disk (Boss, 2002). Small protoplanets torque the disk at the Lindblad and corotation resonances, and the resulting back-torque can propel a planet into the star (Ward, 1997). We investigate the equations of the magneto-rotational instability of the Keplerian disk in linear approximation by qualitative and bifurcation methods. The separation of 3-dimensional parameter space of dynamical system by bifurcation surfaces is obtained. The obtained gallery of more ten phase portraits of disk evolution illustrates the various regimes of the planetary systems evolution. Investigation of a matter around young pulsars will allow us to answer about a possibility of birth of planets after explosion of a supernova star. Title: Spin-Orbital Evolution of Exoplanets Authors: Gusev, A.; Kitiashvili, I. Bibcode: 2003EAS.....6..281G Altcode: We investigated the equation describing the evolution of the kinetic momentum vector of planets by the action of gravitational and magnetic interaction. The obtained gallery of portraits of the kinetic momentum evolution illustrates the various regimes of planetary system evolution. We are going to investigate a fine structure of protoplanetary disk around the pulsar by VLTI for detection of extrasolar planets on early time of formation. Title: Through Kazan ASPERA to Modern Projects Authors: Gusev, Alexander; Kitiashvili, Irina; Petrova, Natasha Bibcode: 2003IAUSS...4E..48G Altcode: Now the European Union form the Sixth Framework Programme. One of its the objects of the EU Programme is opening national researches and training programmes. The Russian PhD students and young astronomers have business and financial difficulties in access to modern databases and astronomical projects and so they has not been included in European overview of priorities. Modern requirements to the organization of observant projects on powerful telescopes assumes painstaking scientific computer preparation of the application. A rigid competition for observation time assume preliminary computer modeling of target object for success of the application. Kazan AstroGeoPhysics Partnership Title: Free core nutation and Chandler wobble of pulsar Authors: Kitiashvili, I.; Gusev, A. Bibcode: 2002cosp...34E1352K Altcode: 2002cosp.meetE1352K In 2000 year Stairs, Lyne and Shemar reported the discovery of the long-term, highly periodic and correlated variations pulse shape and of the rate of slow-down of the pulsar PSR B1828-11 with period variations approximately 1000, 500 and 250 days. According to Stairs et al. (2000), probably, the precession of the spin axis is caused by asymmetry in the shape of the pulsar. It is known that rotation of the terrestrial planets having rigid mantle and elliptical liquid core is characterized by Free Core Nutation (FCN). Therewith any celestial body whose rotation axis does not coincide with the main inertia axis is characterized by Chandler Wobble (CW). These phenomena of FCN and CW are manifested as periodical oscillations of rotation axis of the planet in inertial reference system. For rotating pulsar we deal with the case of modulation of pulses emitted around the direction of the magnetic axis of a pulsar whose symmetry axis does not coincide with the angular velocity vector. We have obtained the periods of PC W and PF C N for different pulsars, correctly extending for neutron star the theory of core-mantle differential rotation of the planets (Petrova &Gusev, 2001). It was made in the frame of Hamiltonian approach for description of rotation of two-layer pulsar having rigid crust and liquid mantle.