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Czech Informel Graphic Art
Krtička, Jiří ; Rakušanová, Marie (advisor) ; Michálek, Ondřej (referee) ; Nešlehová, Mahulena (referee)
The Printmaking of Czech Art Informel Author: Jiří Krtička Abstract The thesis deals comprehensively with the printmaking of Czech Art Informel: explores its sources, principles and themes, evaluates contributions of individual artists and analyses the technique of "structural printmaking". The first artworks in Informel style in Czechoslovakia were created during World War II by Josef Istler who belongs to European protagonists of Art Informel movement. In post-war years Istler engaged mostly in painting and monotyping. For this reason it was Vladimír Boudník who became the leading personality of Czech Informel printmaking. In 1949 he declared in two manifestos of "explosionalism" his vision of a new art that he followed and carried out with admirable consistency till the end of his life. In the middle of 1950s Boudník started to elaborate "structural printmaking" - innovative printmaking methods that became a way to fulfil his vision. His work influenced strongly the whole generation of Czech artists and essentially helped to introduce Art Informel to Czechoslovakia against the ideologic resistance of the communist regime. Czech Informel achieved excellent qualities in Europe-wide comparison and "structural printmaking" became its original contribution to the world fine art. Keywords Art Informel,...
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Physics of X-ray binaries
Čechura, Jan ; Hadrava, Petr (advisor) ; Heyrovský, David (referee) ; Krtička, Jiří (referee)
Title: Physics of X-ray binaries Author: Jan Čechura Department: Astronomical Institute of the Academy of Sciences of the Czech Republic Supervisor: doc. RNDr. Petr Hadrava, DrSc. Abstract: We present a novel observation interpreting method for the high-mass X-ray binaries (HMXBs) based on a combination of spectroscopic data and numerical results of a radiation hydrodynamic model of stellar wind in HMXBs. By using an indirect imaging method of Doppler tomography, we calculate synthetic tomograms of a predicted emission in Low/Hard and High/Soft X-ray states and compare them with tomograms produced using phase-resolved optical spectra of Cygnus X-1, a prototype of HMXBs. The emis- sions of HMXBs are determined by the local conditions within the circumstellar medium - namely by local density, temperature, and ionization parameter. These quantities are computed by the radiation hydrodynamic code and strongly depend on the X-ray state of such systems. By increasing intensity of an X-ray emission produced by the compact companion in the HMXB-model, we achieved a complete redistribution of the circumstel- lar medium in the vicinity of the modelled system. These changes (which simulate the transitions between two major spectral states) are also apparent in the synthetic Doppler tomograms which are in a good...
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Radiation in stellar winds. Resonance line formation in inhomogeneous hot star winds
Šurlan, Brankica ; Kubát, Jiří (advisor) ; Krtička, Jiří (referee) ; Róžaňska, Agata (referee)
Title: Radiation in stellar winds. Resonance line formation in inhomogeneous hot star winds Author: M.Sc. Brankica Šurlan Department: Astronomical Institute of the Academy of Sciences of the Czech Republic Supervisor: RNDr. Jiří Kubát, CSc., Astronomical Institute of the Academy of Sciences of the Czech Republic Abstract: To incorporate the three-dimensional (3-D) nature of stellar wind clump- ing into radiative transfer calculations, in this thesis a newly developed full 3-D Monte Carlo radiative transfer code for inhomogeneous expanding stellar winds is presented and used to investigate how different model parameters influence reso- nance line formation. Realistic 3-D models that describe the dense as well as the rarefied wind components are used to model the formation of resonance lines in a clumped stellar wind. Non-monotonic velocity fields are accounted for as well. It is shown that the 3-D density and velocity wind inhomogeneities have very strong impact on the resonance line formation. The models show that the line opacity is lower for a larger clump separation and shallower velocity gradients within the clumps. They also demonstrate that to obtain empirically correct mass-loss rates from UV resonance lines, wind clumping and its 3-D nature must be taken into account. 1
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Spectral analysis of the B[e] star V743 Mon
Jeřábková, Tereza ; Korčáková, Daniela (advisor) ; Krtička, Jiří (referee)
This thesis deals with the study of the star V743 Mon. Stellar spectrum contains forbidden emission lines of [O I], strong Balmer emission lines and also infrared excess. Due to this, V743 Mon belongs to the group of B[e] objects. Observed spectra indicate very extended and rotating circumstellar envelope composed of gas and dust. We study time variability using data obtained during 2004-2012 at the Astronomical Institue of the Academy of Sciences of the Czech Republic in Ondřejov. We reduce and rectificate these spectra. We mesure relative intensities, equivalent widths and radial velocities for lines Hα, [O I] and Fe II. Graphical description contains also lines Si II and He I. The observed spectra show time variability on both, long- and short-term scales. Spectra from SAAO observatory are used to study the short time-scale changes. The discussion of problems connected with different instruments is also presented. 1
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A study of binary stars with accretion disks
Chadima, Pavel ; Harmanec, Petr (advisor) ; Krtička, Jiří (referee) ; Mourard, Denis (referee)
This thesis contains spectroscopic analyses of two unusual binaries with circum- stellar disks - β Lyr and ǫ Aur. Several hundred optical spectra were processed and analyzed for both binaries which led to several original findings. For β Lyr, it was a discovery of a weak shell spectrum originating in a disk pseudophotosphere and a hidden satellite spectrum, present only during eclipses, which arise from additional absorption of the primary light passing through the gaseous envelope around the secondary. For ǫ Aur, it led to the discovery of the apparent multiperiodic line vari- ability occuring during the current eclipse with a dominant and common period of 66d .21 and to an explanation of complex Hα line profiles during the eclipse which is again caused by an additional absorption of a primary light in an atmosphere of a dark disk around a secondary. Also rich series of radial velocity measurements and photometric observations were collected and used to determine a new precise orbital solution for ǫ Aur. Further, a hydrodynamical and a radiative modeling of a discontinuous mass transfer in a close binary system was carried out which resulted in a formation of an elongated disk with a slow prograde revolution, demonstrated itself by double emission Hα line profiles that exhibit V/R variations.
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Spectroscopy of B[e] star FS CMa
Kříček, Radek ; Korčáková, Daniela (advisor) ; Krtička, Jiří (referee)
B[e] stars are a peculiar group of stars with forbidden emission lines in their spectra. This phenomenon is commonly ascribed as a result of a large shell around the star. FS Canis Majoris (FS CMa) became a prototype of one group of these stars because it was intensively studied in the past. However, in the case of this class of objects current theoretical models of the stellar evolution of a single star are not able to produce such huge amount of circumstellar matter, even if the stellar wind and rapid rotation are included into the calculations. We analysed and rectified some already reduced spectra obtained from 2005 to 2011 at the Astronomical Institute of the Academy of Sciences of the Czech Republic in Ondřejov and at SAAO observatory. Then we focused on the study of short- and long-term time variations of spectral lines in the stellar spectra, measured equivalents widths and radial velocities of the chosen spectral lines and discussed some achieved findings. Especially the short-term time variations of some spectral lines show dynamic processes of the inner star shell.
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Christologic motives in the modern Czech painting and graphic art
Krtička, Jiří ; Pech, Milan (advisor) ; Hlaváčková, Miroslava (referee)
The thesis maps the occurrence of christological motifs in the Czech painting and graphics after 1900 and compares approaches of artists of different generations to their depiction. Selected christological art works are analysed from three main aspects: 1. iconography, 2. style and form, 3. philosophical and psychological resources. A particular chapter deals with christological motifs in modern liturgical art. The conclusion of the work evaluates the significance of the christological theme in context of the modern Czech art development.
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