Seminars 2014
04.03.2014 14:00
Miroslav Horky
Czech Technical University, Prague
Particle-in-Cell (PIC) simulations of instabilities in weakly ionized plasmas
Abstract
Miroslav Horky
Particle-in-Cell (PIC) simulations of instabilities in weakly ionized plasmas
I will talk about the research done during my stay at the University of Oslo. We simulated plasma instabilities in weakly ionized plasmas under the presence of E x B fields. Both, electrons and ions were magnetised in our simulations and we changed only the type of ion-neutral collisions. For these different ion-neutral collision types we found different electron heating rates and other instability characteristics, such as electrostatic potential fluctuations and electrostatic wave spectra. At first I will present theoretical background of our research, then our results and in the end I would like to introduce current analytical study of the simulated instabilities.
04.02.2014 15:00
Norbert Werner
Kavli Institute for Particle Astrophysics and Cosmology, Stanford University
The Astro-H X-ray observatory
Abstract
Norbert Werner
The Astro-H X-ray observatory
I will talk about the upcoming Astro-H satellite, the next large international X-ray observatory. Astro-H will carry the first high-resolution X-ray imaging spectrometers and will provide an unprecedented wide band coverage that will revolutionize the study of the physics of X-ray plasmas. I will summarize the technical capabilities of the satellite and will present some of the most exciting science goals that we expect to reach with this mission.
27.01.2014 15:00
Frantisek Dinnbier
Astronomical Institute, Academy of Sciences, Prague
Propagating star formation in swept-up shells
Abstract
Frantisek Dinnbier
Propagating star formation in swept-up shells
Shells of swept-up gas are commonly observed at borders of HII regions
and interstellar bubbles. As they expand and accrete new mass, they can
fragment and form new stars. If massive stars are formed, they create
new bubbles and this scenario repeats leading to propagation of star
formation. Despite the importance of shell fragmentation, there is no
consonance in literature how long the unstable wavelengths are and how
fast they grow, especially in the case of higher values of pressure that
confines the shell. In my work I study fragmentation of such shells by
hydrodynamic simulations including a self gravity. A shell which is a
subject to my study is thick and stratified in a direction perpendicular
to its surface. At larger distances, it is truncated by the external
pressure from both sides. I will present first results where I study the
fragment growth rate as a function of the external pressure and compare
my results with analytical estimates made by another authors in the past.
20.01.2014 13:00
Jiri Svoboda
Astronomical Institute, Academy of Sciences, Prague
Study of black holes in active galactic nuclei
Abstract
Jiri Svoboda
Study of black holes in active galactic nuclei
We cordially invite all staff and guests of the Astronomical Institute ASCR to the ceremony of Jan Fric Premium for the year 2013.
The ceremony will take place in the library of the Astronomical Institute ASCR in Ondrejov on Monday, January 20, from 13:00. Since 2009, Astronomical Institute grants the Premium of Jan Fric to young researchers of the Institute for their extraordinary results, which contribute to the international prestige of the Institute. The laureate for 2013 is the employee of the Department of Galaxies and Planetary Systems, Dr. Jiří Svoboda. He received the Premium for the study black holes in active galactic nuclei.
07.01.2014 14:00
Vladimír Karas
Astronomical Institute, Academy of Sciences, Prague
Leftovers from the model of spotted accretion discs
Abstract
Vladimír Karas
Leftovers from the model of spotted accretion discs
A `spotted' accretion disc near a black hole has been studied for a long time as a suitable phenomenological scheme to explain a wide range of variability phenomena. Variety of open issues still persist with this scenario. Based on a recent paper (Wellons et al, http://arxiv.org/abs/1312.3333), we discuss a possibility to further explore effects of strong gravity in the X-ray signal from the inner regions of accreting compact objects.
