Tile problem of planctary system formation and its subsequent character can only be addressed by studying the global evolution of solid material entrained in gaseous protoplanetary disks. We start to investigate this problem by considering the space-time development of aerodynamic forces that cause solid particles to dccouple from the gas. The aim of this work is to demonstrate that only the sm...

We made multi-band radio observations of NGC 2997, including total power mapping at λ20 with the Very Large Array (VLA), sensitive polarization observations at λ13 cm with the Australia Telescope Compact Array (ATCA) and images at λ6 and λ3 cm with the VLA. The detected regular magnetic field extends from the centre to the outer disk. In the central part (galactic radius R ≤ 0.5′), the dominate...

High Power microwave vacuum windows are an essential component in developing 1 MW/CW gyrotrons. The thesis focuses on thermal and mechanical analysis of three different microwave window designs. These include the present double disk window, a distributed window being developed by General Atomics and a single-disk diamond window design. The output microwave window is currently the limiting facto...

By analogy with the minimum-mass solar nebula, we construct a surfacedensity profile using the orbits of the 26 precise-Doppler planets found in multiple-planet systems: Σ = 2200 g cm (a/1 AU), where a is the circumstellar radius and β = 2.0 ± 0.5. The minimum-mass solar nebula (β = 1.5) is consistent with this model, but the uniform-α accretion disk model (β ≈ 1) is not. In a nebula with β < 2...

By analogy with the minimum-mass solar nebula, we construct a surfacedensity profile using the orbits of the 26 precise-Doppler planets found in multiple-planet systems: Σ = 2200 g cm (a/1 AU), where a is the circumstellar radius and β = 2.0 ± 0.5. The minimum-mass solar nebula (β = 1.5) is consistent with this model, but the uniform-α accretion disk model (β ≈ 1) is not. In a nebula with β > 2...

The method of constructing of rotation curve for our galactic disk is developed. Simple physical model shows that the velocity of the Sun around the center of the Galaxy must be less than currently accepted IAU value 220 km/s. Independently obtained result for neutral hydrogen (λ = 21.1 cm) confirms the previous statement. The values of the Sun’s velocity is about 110 km/s. As a consequence, th...

Active galaxies are thought to be both fueled and obscured by neutral gas removed from the host galaxy and funneled into a central accretion disk. We performed a VLA imaging survey of 21 cm absorption in Seyfert and starburst nuclei to study the neutral gas in the near-nuclear environment. With the exception of NGC 4151, the absorbing gas traces 100 pc scale, rotating disks aligned with the out...

The feasibility of mid-infrared (MIR) lasing in erbium-doped gallium lanthanum sulfide (GLS) micro-disks was examined. Lasing condition at 4.5 µm signal using 800 nm pump source was simulated using rate equations, mode propagation and transfer matrix formulation. Cavity quality (Q) factors of 1.48 × 10(4) and 1.53 × 10(6) were assumed at the pump and signal wavelengths, respectively, based on s...

We present a radiative transfer model which computes the spectral energy distribution of a passive, irradiated circumstellar disk, assuming the grains are in radiative equilibrium. Dependence on the radial density profile, grain temperature estimation, and optical depth profiles on the output SED are discussed. The best fit model for HR 4796A has a minimum and maximum spherical grain size of 2....