Pravidelné semináře pořádáme jednou měsíčně (říjen–červen, zpravidla první pondělí v měsíci) od 13 hod v seminární místnosti pracoviště Ondřejov. (archiv seminářů)
13. 02. 2012
Formation of the AGN torus in a nuclear starburst environment.
Abstract: I will present a hydrodynamical model for the formation of the gaseous
torus in active
galactic nuclei from the matter reinserted by a rotating young nuclear
star cluster (NSC). In the model, a NSC evolving in a catastrophic
cooling regime is a necessary condition for the formation of the
torus. By using typical
parameters of NSCs (mass, size, etc,... ) and black holes (BHs) in
Seyfert galaxies, the model predicts sizes and thickness for the tori as those
inferred from observations. An analytic formula to estimate the
radius at which mass accumulates and forms the torus will
be presented as well.
Dále pořádáme menší semináře jednotlivých oddělení:
Semináře slunečního oddělení
Každé úterý v 12:45 (září–červen, s výjimkou úterků po celoústavním semináři) v zasedací místnosti slunečního oddělení pracoviště Ondřejov.
07/02/2012, 13:00Proton energetics in the solar wind between 0.3 and 1 AU: Helios reloadedAbstract: The proton thermal energetics in the solar wind between 0.3 and 1 AU is re-investigated using the Helios 1 and 2 data. Heating and cooling rates are evaluated for the slow and fast solar wind and discussed in the context of the solar wind turbulence. Possible influence of the interaction between fast and slow solar wind streams on the proton energetics is discussed.
Zářivě-(magneto)hydrodynamické semináře
Zpravidla 1x za 14 dní ve čtvrtek od 11 hod (říjen–červen) v zasedací místnosti slunečního oddělení pracoviště Ondřejov.
01/12/2011, 11:00Konkoly Observatory, Budapest, HungaryThe extreme outburst of the young eruptive star EX Lupi in 2008Abstract: EX Lupi is the prototype of EXors, a spectacular group of low-mass pre-main sequence stars characterized by repetitive optical outbursts of 1-5 mag lasting for a few months-to-few years. The outburst is attributed to enhanced accretion from the inner circumstellar disk (within ^X0.1AU) to the stellar surface, probably triggered by an instability in the disk. The historically largest outburst of EX Lupi in 2008 Jan-Sep offered a unique opportunity to understand deeper the physics of the EXor eruptions. In my talk I will summarize the main results of our coordinated observing campaign, in which we used a large set of telescopes to observe and characterize the path of accretion from the disk onto the stellar surface, with the aim of comparing the different models of outburst physics. Our measurements also demonstrated that the brief episodes of highly increased accretion, apart from contributing to the build-up of the final stellar mass, have substantial effect on the structure and composition of the circumstellar material: We discovered episodic crystallization of silicate grains in the disk surface due to the increased luminosity during the 2008 outburst, resulting in material that forms the building blocks of comets and planets.
Semináře oddělení GPS
Zpravidla v knihovně pracoviště Praha–Spořilov v různé dny.
06. 02. 2012, 13:00Astronomical Institute, Academy of Sciences, PragueMagnetized accretion toriAbstract: We are carrying out a student project concerning the study of accretion of two-dimensional magnetized tori with a radially increasing angular momentum density, l(R). We discuss differences between these tori and those with l=const. In an informal talk we will present the progress and the current status of the project, as well as open questions.(Takes place at: Sporilov library)