We investigate the model of the disc/corona accretion flow around the black hole. Hot accreting advective corona is described by the two-temperature plasma in pressure equilibrium with the cold disk. Corona is powered by accretion but it also exchanges energy with the disk through the radiative interaction and conduction. The model, parameterized by the total (i.e. disk plus corona) accretion r...

We present high resolution time-resolved optical spectra of the high inclination short orbital period dwarf nova V893 Sco. We performed spectral analysis through radial velocity measurements, Doppler mapping, and ratioed Doppler maps. Our results indicate that V893 Sco's accretion disk is dissimilar to WZ Sge's accretion disk, and does not fit any of the current accretion disk models. We derive...

The evolution of a stellar disk under the influence of viscous evolution, photoevaporation from the central source, and photoevaporation by external stars is studied. We take the typical parameters of TTSs and the Trapezium Cluster conditions. The photoionizing flux from the central source is assumed to arise both from the quiescent star and accretion shocks at the base of stellar magnetospheri...

Gas giant planets have been detected in orbit around an increasing number of nearby stars. Two theories have been advanced for the formation of such planets: core accretion and disk instability. Core accretion, the generally accepted mechanism, requires several million years or more to form a gas giant planet in a protoplanetary disk like the solar nebula. Disk instability, on the other hand, c...

The effects of binary tidal forces on transport within an accretion disk are studied with a time-dependent hydrodynamical model of a two-dimensional isothermal accretion disk. Tidal forces quickly truncate the accretion disk to radii of order half the average radius of the Roche lobe, and excite a two-armed spiral wave that remains stationary in the rotating reference frame of the binary system...

The SW Sextantis stars are a group of cataclysmic variables with distinctive observational characteristics, including absorption features in the emission line cores at phases 0.2–0.6. Hellier and Robinson have proposed that these features are caused by the accretion stream flowing over the accretion disk. However, in a simple model the absorption occurred at all orbital phases, which is contrad...

We discuss the properties of an accretion disk around a star with parameters typical of classical T Tauri stars (CTTS), and with the average accretion rate for these disks. The disk is assumed steady and geometrically thin. The turbulent viscosity coefficient is expressed using the α prescription and the main heating mechanisms considered are viscous dissipation and irradiation by the central s...

We investigate dust dynamics and evolution during the formation of a protostellar accretion disk around intermediate mass stars via 2D numerical simulations. Using three different detailed dust models, compact spherical particles, fractal BPCA grains, and BCCA grains, we find that even during the early collapse and the first ∼ 10 yr of dynamical disk evolution, the initial dust size distributio...

To investigate the geometry of the accretion disk in the source H1743-322, we have carried out a detailed X-ray temporal and spectral study using RXTE pointed observations. We have selected all data pertaining to the Steep Power Law (SPL) state during the 2003 outburst of this source. We find anti-correlated hard X-ray lags in three of the observations and the changes in the spectral and timing...

We discuss plausible mechanisms to produce bullet-like ejecta from the precessing disk in the SS 433 system. We show that non-steady shocks in the subKeplerian accretion flow can provide the basic timescale of the ejection interval while the magnetic rubber-band effect of the toroidal flux tubes in this disk can yield flaring events. Subject headings: accretion, accretion disks — hydrodynamics ...