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.

Ve své přednášce stručně shrnu naše nové výsledky, které jsme letos opublikovali, resp. máme zaslány k publikaci, případně jsou v revizi. V práci [1] jsme studovali rozložení pólů drah binárních asteroidů na vzorku 18 z nich, které jsme pozorovali z Ondřejova a spolupracujících stanic. Zjistili jsme, že jejich póly jsou rozloženy značně nerovnoměrně, koncentrují se v okolí do 30 stupňů od pólů ekliptiky. Navrhli jsme, že jde o důsledek působení YORP efektu, který "narovnává" rotační osy jejich mateřských těles (pre-formation mechanism), případně hlavních složek -primárů- binárních systémů (post-formation mechanism). V práci [2] jsme prozkoumali zkreslení v odhadech albed asteroidů, která získal tým Mainzer et al. (Astrophys. J. 741, 90, 2011) modelováním infračervených měření z družice WISE. Analýzou srovnávacího vzorku 583 asteroidů, jejichž absolutní magnitudy jsme změřili z Ondřejova a z Table Mountain Observatory v Kalifornii, jsme zjistili, že jejich odhadovaná albeda jsou systematicky přeceněná a revidovali jsme je. Odvodili jsme, že střední geometrické V albedo asteroidů S typu je 0.197 ± 0.006 a že se s velikostí asteroidu (v intervalu průměrů 0.6-200 km) významně nemění; tím jsme opravili předchozí omyl týmu Mainzer et al.. V práci [3] jsme pak analyzovali možnost detekce binárních asteroidů metodou oscilace fotocentra z ultra-přesných astrometrických měření družicí Gaia. Ukázali jsme, že při dosažení plánované astrometrické přesnosti 2*10^(-5) až 1*10^(-3) obloukové vteřiny (v závislosti na jasnosti objektu) bude možno v jejích datech detekovat periodickou oscilaci fotocentra způsobenou oběhem složek bináru pro středně vzdálené satelity s periodami v řádu dní. Populace těchto středně širokých binárů je dosud do značné míry nepopsaná, protože dosavadní observační techniky (fotometrie, adaptivní optika) mají v jejich oblasti parametrů nízkou či nulovou účinnost. (Literatura: [1] Pravec P., Scheirich P., Vokrouhlicky D., Harris A.W., et al., Binary Asteroid Population. 2. Anisotropic distribution of orbit poles of small, inner main-belt binaries. Icarus 218 (2012) 125-143, [2] Pravec P., Harris A.W., Kusnirak P., Galad A., Hornoch K., Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations. Icarus, submitted. [3] Pravec P., Scheirich P., Small binary asteroids and prospects for their observations with Gaia, Planet. Space Sci., in revision)

The magnetic nature of sunspots was discovered by G.E. Hale in 1908. Since then, the magnetic field properties were thoroughly studied. I will present the summary of magnetic field properties in sunspots along with brief explanation how to determine the vector of magnetic field in solar photosphere. The aim of our analysis was to determine the magnetic field properties on penumbral boundaries, which were not yet studied explicitly. We tried to determine if the magnetic field strength or inclination is constant on these boundaries and if these values are dependent on sunspot size. The most important result is that the inner penumbral boundaries are defined by the critical value of the vertical component of the magnetic field. This implies that the penumbral filaments have a convective origin.

Magnetic massive stars experience confinement of stellar wind plasma by their strong, large-scale magnetic fields. This magnetospheric material can produce observable spectral and photometric effects in wavelengths from X-rays to radio. I will present a summary of the observational and theoretical efforts to study massive star magnetospheres, as well as discuss future possibilities for these stars in the infrared.

We study an astrophysical model consisting of the rotating black hole immersed into the asymptotically uniform magnetic field. Structure of the electromagnetic field emerging in the generalized setup involving the oblique background field (misaligned with the rotation axis) and translational motion of the black hole is explored in detail. For a sufficiently rapid drift we localise separator null points of both electric and magnetic fields. The latter are of an utmost interest since they prove that the interplay of the rotation and the drift of the compact body may act as a trigger for magnetic reconnection. Subsequently we study the motion of charged particles in the simplified setup of aligned field. We concern ourselves mainly with the dynamic properties of the trajectories bound in the off-equatorial potential lobes which are relevant for a description of diluted astrophysical coronae. Employing the recurrence analysis we locate transitions between regular and chaotic regimes of motion. Besides the bound off-equatorial orbits we also study trajectories escaping from the equatorial plane in the collimated jet-like structures.

Deceleration of meteors is a common effect directly observable from their photographic or video records. This is due to the fact that these techniques are capable of covering their whole visible trajectory as a function of time. Contrary to photographic or video meteors their radar observations yield only time and velocity at selected points depending on the configuration of the observing system. Very important in this respect is the method of velocity determination. We compare two of them and discuss their possibilities. The knowledge of sufficiently reliable radar meteor velocities at different points of trajectory enables to determine meteoroid deceleration and, consequently, to compute its heliocentric orbit. The results of application of such approach to the data from CMOR are presented.

The spectrum of the Be star o Pup is shown to vary periodically with a period of 28.9 days. A radial-velocity variable He I 6678 A emission component suggests that the star is the same type as phi Per, 59 Cyg and FY CMa, i.e. binaries consisting of a Be star and a hot companion that illuminates the Be star disk (also called phi Per-type binaries or Be+sdO binaries). The range of radial-velocity variations of the stronger emission component in the helium line observed in o Pup is about 270 km/s, a value which is in good agreement with the range derived for phi Per-type binaries. The radial velocity curves defined by the prominent emission peak in He I 6678 A line and H alpha + Paschen emission move in anti-phase. We suggest that o Pup is generically similar to phi Per-type systems and may represent the fourth case of a Be star with a hot subdwarf companion.