Stellar Winds and Galactic Superwinds
Astrophysical flows, driven by the injection of mass, momentum and energy from either individual stars or groups of stars occur over a vast range of spatial and energy scales. On the smallest scales, hypersonic winds from massive stars in binary systems collide and generate X-ray emission from the very hot shocked gas. On larger scales, these winds interact with the local circumstellar or interstellar medium (ISM) to produce wind-blown bubbles (WBBs), and supernova ejecta interact with the local ISM or nuclear winds in the central regions of active galaxies. On the largest scales, multiple supernova events generate highly pressurized regions which power superwinds that flow out of galaxies into intergalactic space. Although these phenomena are astrophysically very distinct, there are common features in the physics and hydrodynamics that make a broad approach to their study feasible and appropriate. For example, many of the flows occur in astrophysical media where cool clumps are embedded in a hotter substrate and an understanding of mass injection from these clumps is essential. Theoretical studies of these flows are accompanied by careful comparison with observational data to verify the complex physical and hydrodynamical modelling used.
A hydrodynamic simulation of colliding stellar winds.
Mass-loss from Massive Stars
The most massive stars are central to a host of important astrophysical problems (e.g., the chemical evolution of the Galaxy, and the birth of stellar mass black holes). A crucial parameter critical to their evolution and their environmental impact is the rate at which they lose mass through their powerful winds and outbursts. The wind-wind collision in interacting binary stars is a powerful probe of the mass-loss from the most massive stars. This is illustrated in the article on Eta Carinae in the "See also..." section.Galactic Superwinds
The galactic superwind in NGC 3079.
On large scales, superwinds are created when supernova remnants (SNRs) within star-forming regions overlap to create highly pressurized superbubbles which burst out into intergalactic space. Superwinds are important re-distributors of heavy elements, mass, and momentum, and their role in enriching and heating the intergalactic medium is attracting much attention. There is currently great debate on the physical origin of their X-ray emission. We are addressing this issue using a novel approach based on the ranges of SNRs evolving in an inhomogeneous medium. Such models should resolve some of the outstanding issues and will aid the use of X-ray observations as diagnostics of starburst superwinds.
Suggested Reading
The following books have several chapters which are relevant to research of astrophysical winds and galactic superwinds:
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Blowing Bubbles in the Cosmos
Astronomical Winds, Jets, and Explosions
Published January 2004, 208 pages Oxford University Press |
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The Physics of the Interstellar Medium
Published September 1997, 170 pages The Institute of Physics |
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