Related papers: Non-isothermal effects on Be disks
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…
We investigate the structure of accretion disks around massive protostar applying steady state models of thin disks. The thin disk equations are solved with proper opacities for dust and gas taking into account the huge temperature…
Complex organic molecules are only detected toward a fraction of high-mass protostars. The goal of this work is to investigate whether high-mass disks can explain the lack of methanol emission from some massive protostellar systems. We…
We present a self-consistent analytical model for the computation of the physical conditions in a steady quasi-Keplerian accretion disk. The method, based on the thin disk approximation, considers the disk as concentric cylinders in which…
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…
Few circumstellar disks have been directly observed. Here we use sensitive differential polarimetric techniques to overcome atmospheric speckle noise in order to image the circumstellar material around HD 169142. The detected envelope or…
We present multi-wavelengths observations and a radiative transfer model of a newly discovered massive circumstellar disk of gas and dust which is one of the largest disks known today. Seen almost edge-on, the disk is resolved in…
In this chapter, I present a summary of observational tests of the basic picture of disk accretion. An emphasis is placed on tests relevant to black holes, but many of the fundamental results are drawn from studies of other classes of…
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…
We examine Be star discs in highly eccentric Be/X-ray systems. We use a three-dimensional smoothed particle hydrodynamics (SPH) code to model the structure of the Be star disc and investigate its interactions with the secondary star over…
We present a model that describes stellar infrared excesses due to heating of the interstellar (IS) dust by a hot star passing through a diffuse IS cloud. This model is applied to six lambda Bootis stars with infrared excesses. Plausible…
Some transition disks host misaligned inner disks with radii of several au. Understanding the geometric and physical properties of these misaligned disks is essential for advancing terrestrial planet formation models. This study introduces…
The dust in protoplanetary disks is an important ingredient in planet formation and can be investigated with model simulations and quantitative imaging polarimetry of the scattered stellar light. This study explores circumstellar disks with…
The quantity of dust in a spiral disk can be estimated using the dust's typical emission or the extinction of a known source. In this paper, we compare two techniques, one based on emission and one on absorption, applied on sections of…
Binarity in massive stars has proven to be an important aspect in the their evolution. For Be stars, it might be the cause of their spin up, and thus part of the mechanism behind the formation of their viscous decretion disks. Detecting…
This paper is one in a series reporting results from small telescope observations of variable young stars. Here, we study the repeating outbursts of three likely Be stars based on long-term optical, near-infrared, and mid-infrared…
While the presence of discs around classical Be stars is well established, their origin is still uncertain. To understand what processes result in the creation of these discs and how angular momentum is transported within them, their…
The imaging of disks around young stars presents extreme challenges in high dynamic range, angular resolution, and sensitivity. Recent instrumental advances have met these challenges admirably, leading to a marked increase in imaging…
We discuss the importance of accretion in calculating disk models for young stellar objects. In particular, we show that a disk inner rim, irradiated by both the star and the accretion shocks at the stellar surface, can naturally explain…
We are investigating the circumstellar material for a sample of B[e] stars using high spectral resolution data taken in the optical and near-infrared regions with ESO/FEROS and ESO/CRIRES spectrographs, respectively. B[e] stars are…