Viscosity in accretion discs and HD 101584.
نویسندگان
چکیده
منابع مشابه
The dependence of the viscosity in accretion discs
We estimate the Shakura-Sunyaev viscosity parameter alpha for diierent values of the shear/vorticity ratio, =!, using local simulations of dynamo-generated turbulence. We nd that the time average of is approximately proportional to =! (at least for =! < 10). We point out that this result may have important implications for the properties of thick accretion discs, because there ! is small and wo...
متن کاملThe dependence of the viscosity in accretion discs on theshear /
We estimate the Shakura-Sunyaev viscosity parameter alpha for diierent values of the shear/vorticity ratio, =!, using local simulations of dynamo-generated turbulence. We nd that the time average of is approximately proportional to =! (at least for =! < 10). We point out that this result may have important implications for the properties of thick accretion discs, because there ! is small and wo...
متن کاملThe circumstellar molecular envelope of HD 101584
CO radio line observations reveal a molecular gas envelope around the peculiar star HD101584 with characteristics very similar to those of wellknown young post-AGB objects. We estimate that there is at least 0.1 M of molecular gas, very likely remnant gas from a former AGB-envelope. This gas has been efficiently accelerated to very high velocities (>50 km s−1, and a significant fraction to >100...
متن کاملModelling magnetised accretion discs
Some recent results are reviewed that lead us now to believe that accretion discs are basically always magnetised. The main components are Balbus-Hawley and Parker instabilities on the one hand and a dynamo process on the other. A mechanical model for the Balbus-Hawley instability is presented and analysed quantitatively. Three-dimensional simulations are discussed, especially the resulting mag...
متن کاملSelf-gravitating accretion discs
— I review recent progresses in the dynamics and the evolution of self-gravitating accretion discs. Accretion discs are a fundamental component of several astrophysical systems on very diverse scales, and can be found around supermassive black holes in Active Galactic Nuclei (AGN), and also in our Galaxy around stellar mass compact objects and around young stars. Notwithstanding the specific di...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1977
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/180.2.141