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Spectroscopic diagnosis of extended circumstellar regions about early type stars
Dvořáková, Nela ; Korčáková, Daniela (advisor) ; Zasche, Petr (referee)
Nela Dvořáková 19.7.2019 1 Abstract We study a representative of a diverse group of stars exhibiting the B[e] phe- nomenon, designated MWC 939. This object might be an important link be- tween the stage of the asymptotic giant branch and planetary nebula stage as it is one of a few such objects observed. Our focus is aimed at spectral analysis of the circumstellar matter around the central star. We assemble a line list for MWC 939 and observe variations of its spectrum. Electron density and temper- ature are estimated using nebular diagnostics of ratios of [S II] λλ 6716, 6731 ˚A and [O I] λλ 6300, 6364 ˚A and 5577 ˚A. These estimates are then used for detailed calculations of the structure of circumstellar envelope. 1
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Tidal heating in icy bodies of the Solar System
Dvořáková, Nela ; Čadek, Ondřej (advisor) ; Čížková, Hana (referee)
1 Abstract The thesis concerns with icy moons and the computation of the heat production which is generated by the effect of tidal forces. The text primarily focuses on the behaviour of viscosity in the ice shell for variable ice shell thickness. Viscosity decreases exponentially as the temperature of ice increases. We also study the viscosity and heat dependence on the size of an ice grain in range of 10−5 m - 10−1 m and the amount of stress in range of 103 Pa - 107 Pa. Computation was realized using a provided program and the results of all models are represented in form of a heat map and further studied. Primarily we discuss the heat balance of the moon Europa and Enceladus. 1
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Spectroscopic diagnosis of extended circumstellar regions about early type stars
Dvořáková, Nela ; Korčáková, Daniela (advisor) ; Zasche, Petr (referee)
Nela Dvořáková 19.7.2019 1 Abstract We study a representative of a diverse group of stars exhibiting the B[e] phe- nomenon, designated MWC 939. This object might be an important link be- tween the stage of the asymptotic giant branch and planetary nebula stage as it is one of a few such objects observed. Our focus is aimed at spectral analysis of the circumstellar matter around the central star. We assemble a line list for MWC 939 and observe variations of its spectrum. Electron density and temper- ature are estimated using nebular diagnostics of ratios of [S II] λλ 6716, 6731 ˚A and [O I] λλ 6300, 6364 ˚A and 5577 ˚A. These estimates are then used for detailed calculations of the structure of circumstellar envelope. 1
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Tidal heating in icy bodies of the Solar System
Dvořáková, Nela ; Čadek, Ondřej (advisor) ; Čížková, Hana (referee)
1 Abstract The thesis concerns with icy moons and the computation of the heat production which is generated by the effect of tidal forces. The text primarily focuses on the behaviour of viscosity in the ice shell for variable ice shell thickness. Viscosity decreases exponentially as the temperature of ice increases. We also study the viscosity and heat dependence on the size of an ice grain in range of 10−5 m - 10−1 m and the amount of stress in range of 103 Pa - 107 Pa. Computation was realized using a provided program and the results of all models are represented in form of a heat map and further studied. Primarily we discuss the heat balance of the moon Europa and Enceladus. 1
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