Related papers: On outflowing viscous disc models for Be stars
We study the outflow of dust particles on the surface layers of optically thick disks. At the surface of disks around young stars, small dust particles (size < 10 micron) experience stellar radiation pressure support and orbit more slowly…
The mechanism of X-ray outbursts in Be X-ray binaries remains a mystery, and understanding their circumstellar disks is crucial for a solution of the mass-transfer problem. In particular, it is important to identify the Be star activities…
UV radiation from OB stars can drive ``external'' photoevaporative winds from discs in clusters, that have been shown to be important for disc evolution and planet formation. However, cluster dynamics can complicate the interpretation of…
Magnetorotational turbulence and magnetically driven disc winds are often considered as separate processes. However, realistic astrophysical discs are expected to be subject to both effects, although possibly at different times and…
We use a smoothed particle hydrodynamics (SPH) code to examine the effects of misaligned binary companions on Be star discs. We systematically vary the degree of misalignment between the disc and the binary orbit, as well as the disc…
The main theoretical problem for the formation of a Keplerian disk around Be stars is how to supply angular momentum from the star to the disk, even more so since Be stars probably rotate somewhat sub-critically. For instance, nonradial…
The formation of galactic discs and the efficiency of star formation within them are issues central to our understanding of galaxy formation. We have developed a detailed and versatile model of disc formation which combines the strengths of…
Be stars are thought to be fast rotating stars surrounded by an equatorial disc. The formation, structure and evolution of the disc are still not well understood. In the frame of single star models, it is expected that the surface of an…
Young stars are associated with prominent outflows of molecular gas. The ejection of gas via these outflows is believed to remove angular momentum from the protostellar system, thus permitting young stars to grow by accretion of material…
We study a self-similar circulation model for protostellar bipolar outflows. The model is axisymmetric and stationary, and now includes Poynting flux. Compared to an earlier version of the model, this addition produces faster and more…
Hot stars are the main source of ionization of the interstellar medium and its enrichment due to heavy elements. Constraining the physical conditions of their environments is crucial to understand how these stars evolve and their impact on…
The formation of massive stars exceeding 10 solar masses usually results in large-scale molecular outflows. Numerical simulations, including ionization, of the formation of such stars show evidence for ionization-driven molecular outflows.…
Photoevaporation of planet forming discs by high energy radiation from the central star is potentially a crucial mechanism for disc evolution and it may play an important role in the formation and evolution of planetary system. We present…
Magnetic fields on hot stars can produce a variety of interesting effects on the velocity, density, and temperature structure in the winds from the stars. The fields can produce a longitudinal dependence of the mass flux, which would lead…
We use the three-dimensional Monte Carlo radiative transfer code HDUST to model Be stars where the disc is tilted from the equatorial plane of the star. We compute 128 models across 4 spectral types, B0, B2, B5 and B8, tilting the disc by…
This paper describes a practical model for the polarization of Be stars which can be used to estimate roughly the physical parameters for optically thin circumstellar envelopes from broadband UBVRI photopolarimetry data. Analysis of…
The theory of radiation driven wind including stellar rotation is re-examined. After a suitable change of variables, a new equation for the mass loss rate is derived analytically. The solution of this equation remains within 1% confidence…
Observations of jets from young stellar objects reveal the asymmetric outflows from some sources. A large set of $2.5$D MHD simulations has been carried out for axisymmetric viscous/diffusive disc accretion to rotating magnetized stars for…
We summarize recent 2D MHD simulations of line-driven stellar winds from rotating hot-stars with a dipole magnetic field aligned to the star's rotation axis. For moderate to strong fields, much wind outflow is initially along closed…
The evolution of protoplanetary disks is dominated by the conservation of angular momentum, where the accretion of material onto the central star is driven by viscous expansion of the outer disk or by disk winds extracting angular momentum…