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Bulgarian Academy of Sciences Space Research and Technology
Institute
Astrophysics and Space Dynamics Astrophysics and Space Dynamics DepartmentDepartment
BULGARIAN ACADEMY OF SCIENCESSPACE RESEARCH AND TECHNOLOGY INSTITUTEAcad. G. Bonchev Str., Bl. 1, 1113 Sofia, Bulgaria; tеl./fax:: +359 2 988 35 03; е-mail: [email protected], http://www.space.bas.bg
Processed complete all results for key moments t = 1P and t ≈ 0 indicates that the disk develops spherical radiative (non-
convective) corona. We analyze the influence of the structure on stream in the primary component, the hot advection accretion disk, over the adaptation in the equations on the secondary
component – corona.
Results of magneto-hydrodynamical approximation
Vertical boundary distributions of the function of the equatorial density
Cylindrical boundary contours of the function of the equatorial density
Doppler Tomography: To construct the true cart of image of the obtained data; to derive the radiation intensity distribution in the system’s velocity space, making it possible to determine the parameters of the main flow elements in which energy is released.
The figure presents the 2D simulation of vorticity time evolution in the accretion flow. The picture visualizes a single vortex formation, which is a part of pattern configuration frame in the final stage of its evolution
The 3D view (behavior) of the same “vortex”. The “vortex”-like formation is presented as a patch in the calculating mesh grid.
Study of the Driving forces- stabilization and disruptive modes Systems’ Evolution Hierarchies- their Transitional Stages and Time scales Time- "periodicity"- paradoxes in the structure of an astrophysical system’s activity The trigger effects from: Interstellar dust properties, giant planets’ & sudden energy release (GRB) influence on: IPM, magnetic field generation & planetary atmospheres A Study of Possible Scenarios as a Result of Rapid and/or Burst-like, Long-term
a bifurcation is any qualitative or topology reconstruction of the system, when the parameter of the system crosses its critical value. When a given system passes through a bifurcation point, it may lose its stability. It is seen in the figure this transition trough the critical point.
-80-60
-40-20
020
4060
80
lambda(c)
-40-20
020
4060
80100
120
w(c)
-4
-2
0
2
4Psi(r)
The bifurcation theory is a powerful tool for analyzing the nonlinear evolution of instability behavior in pattern forming systems.
a broad variety of objects: shocks in stellar winds, their interaction with the interstellar matter; supernova remnants. Since the gas flows in the studied objects are highly supersonic, the postshock temperatures are of the order of a million Kelvin and even much higher, therefore, the primary shock emission is in X-rays.
All the observations that are part of this science project are done with the modern X-ray observatories Chandra (NASA) and XMM-Newton (ESA), as the three basic subprojects are as the following.
Physics of Shocks in Astrophysical objects Research Projects and results
Physics of Shocks in Astrophysical objects Research Projects and results
• Monitoring the birth of the supernova remnant in the Large Magelanic Cloud (SNR 1987A)
A new phenomenological model is being developed that is capable of explaining the observed X-ray emission and how it is related to the shock emission in other spectral domains.
The observations are done as part of numerous projects with the Chandra X-ray observatory (PI: Prof. D. Burrows, The Pennsylvania State University, USA for the imaging in 2000 - 2009; PI: Prof. R. McCray, University of Colorado at Boulder, USA for the spectral observations in 2004-2007) The figure is published in S. Zhekov et al. (2004, Astrophysical Journal, 628, L127-L130).
Physics of Shocks in Astrophysical objects Research Projects and results
WR+O binaries are one of the brightest X-ray sources amongst the massive stars. Their enhanced emission originates from the interaction region of the winds of the two massive stars. A phenomenon called colliding stellar winds(CSW) being an ideal laboratory for studying the shock physics.
A new CSW model (see Figure) was used to analyse the X-ray spectrum of the massive binary system WR 147 that was obtained with the XMM-Newton X-ray observatory (PI: Dr. S. Skinner, University of Colorado at Boulder, USA). The figure is from S. Zhekov (2007, MNRAS, 382, 886-894).
Physics of Shocks in Astrophysical objects Research Projects and results
• X-ray emission from single massive stars
It was used for analysis of a sample of 15 massive OB stars. The data were taken from the archive of the Chandra observatory. X-ray spectra of presumably single WR stars were analysed over the years. These projects are based on data taken with Chandra and XMM-Newton X-ray telescopes (PI: PI: Dr. S. Skinner, University of Colorado at Boulder, USA).
The present concept on theorigin of X-rays in massive stars (OB and Wolf-Rayet) posits that they are emitted by hot gas heated by shocks. OB and WR stars possessmassive and fast winds driven by radiation pressure and subject to instabilities (radiation-driven instabilities) which may give rise to the formation of strong shocks.
Project “Аccretion” – Nonlinear dynamics of accretion flows in binary Project “Аccretion” – Nonlinear dynamics of accretion flows in binary star systems”. International scientific project between SRTI - BAS star systems”. International scientific project between SRTI - BAS and Institute of Astronomy of the Russian Academy of Sciences and Institute of Astronomy of the Russian Academy of Sciences
(2006-2015).(2006-2015).
Projects
Based on these results there are many publications and two Based on these results there are many publications and two theses are supported in the past three years.theses are supported in the past three years.
COST action MP 1104: Polarisation as a tool to study the Solar System and beyond
ERC Starting Grant 2014: Instability processes in stellar systems with compact objects. Theoretical and observational investigations. Submitted to Horizon 2020