Related papers: Non-LTE Monte Carlo Radiative Transfer: II. Non-Is…
We apply the viscous decretion disc (VDD) model to interpret the infrared disc continuum emission of 80 Be stars observed in different epochs. In this way, we determined 169 specific disc structures, namely their density scale, $\rho_0$,…
With a series of numerical simulations, we analyze the thermo-hydrodynamical evolution of circumstellar disks containing Jupiter-size protoplanets. In the framework of the two-dimensional approximation, we consider an energy equation that…
Eccentric Keplerian discs are believed to be unstable to three-dimensional hydrodynamical instabilities driven by the time-dependence of fluid properties around an orbit. These instabilities could lead to small-scale turbulence, and…
We investigate the viscous stability of thin, Keplerian accretion disks in regions where general relativistic (GR) effects are essential. For gas pressure dominated (GPD) disks, we show that the Newtonian conclusion that such disks are…
We investigate the nonlinear growth stages of bending instability in stellar disks with exponential radial density profiles.We found that the unstable modes are global (the wavelengths are larger than the disk scale lengths) and that the…
The collapse of interstellar gaseous clouds towards a protostar leads to the formation of accretion disks around the central star. Such disks can be dynamically stable if they settle in an axisymmetric state. In this letter, we investigate…
Recent work by Pringle and by Maloney, Begelman & Pringle has shown that geometrically thin, optically thick, accretion disks are unstable to warping driven by radiation torque from the central source. In this paper we generalize the study…
We have calculated several representative models of vertical structure of an accretion disk around a supermassive Kerr black hole. The interaction of radiation and matter is treated self-consistently, taking into account departures from LTE…
The effects of gravitational darkening on the thermal structure of Be star disks of differing densities are systematically examined. Gravitational darkening is the decrease of the effective temperature near the equator and the corresponding…
The linear stability of accretion disks is revisited. The governing equations are expanded asymptotically and solved to first order in the expansion parameter $\epsilon$ defined by the ratio of the disk's vertical thickness to its radial…
We have computed radiative equilibrium models for the gas in the circumstellar envelope surrounding the hot, classical Be star $\gamma $Cassiopeia. This calculation is performed using a code that incorporates a number of improvements over…
Using the anelastic approximation of linearized hydrodynamic equations, we investigate the development of axially symmetric small perturbations in thin Keplerian discs. Dispersion relation is found as a solution of general Sturm-Liouville…
We describe an analytic model for an evolving protoplanetary disk driven by viscosity and a disk wind. The disk is heated by stellar irradiation and energy generated by viscosity. The evolution is controlled by 3 parameters: (i) the inflow…
Most analytic work to date on protostellar disks has focused on those in isolation from their environments. However, observations are now beginning to probe the earliest, most embedded phases of star formation, during which disks are…
The vertical density distribution of stars in a galactic disc is traditionally obtained by assuming an isothermal vertical velocity dispersion of stars. Recent observations from SDSS, LAMOST, RAVE, Gaia etc show that this dispersion…
This paper presents a detailed statistical determination of the equatorial rotation rates of classical Be stars. The rapid rotation of Be stars is likely to be linked to the ejection of gas that forms dense circumstellar disks. The physical…
A certain appeal to the alpha model for turbulence and related viscosity in accretion disks was that one scales the Reynolds stresses simply on the thermal pressure, assuming that turbulence driven by a certain mechanism will attain a…
We investigate structure of self-gravitating disks, their fragmentation and evolution of the fragments (the clumps) using both analytic approach and three-dimensional radiation hydrodynamics simulations starting from molecular cores. The…
The linear instability of thin, vertically-isothermal Keplerian discs, under the influence of axial magnetic field is investigated. Solutions of the stability problem are found explicitly by asymptotic expansions in the small aspect ratio…
Mass loss appears to be a common phenomenon among disk-accreting astrophysical systems. An outflow emanating from an accretion disk can act as a sink for mass, angular momentum and energy and can therefore alter the dissipation rates and…