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Lookup NU author(s): Professor Axel Brandenburg,
Professor Anvar Shukurov
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The evolution of a superbubble is simulated using a local three-dimensional, non-ideal MHD model, which includes galactic differential rotation, an external gravitational potential, heating via supernova explosions and radiative cooling of the interstellar medium (ISM). In our model a superbubble is formed due to the clustering of supernova activity, mimicking an OB association. Supernovae are modelled as instantaneous explosions that release 1051erg of thermal energy and 3M⊙ of gas in a small volume. We implement a superbubble with the luminosity 3 × 1037erg s-1 into an initial ISM, which is taken from our earlier calculations modelling the warm and hot phases of the ISM. The simulated ISM has a multi-phase structure with hot, dilute and warm, denser gas coexisting in pressure equilibrium; there is also some cold, dense gas in the form of clouds and filaments arising from supernova compression. The multicomponent gas is in a state of developed turbulence, with r.m.s. velocity 10 and 40km s-1 for the warm and hot gas, respectively. At the developed state of the simulation there is a magnetic field of 1.3μG strength having both uniform and random components. The evolution of a superbubble is rather different from that indicated by models with quasi-uniform ambient medium. The superbubble loses its spherical symmetry at very early stages of expansion. Its break-through from the disc is strongly facilitated by the nonuniformity of its environment. A superbubble which would be confined in the disc according to criteria obtained for a quasi-uniform ISM can break out to the halo.
Author(s): Korpi MJ, Brandenburg A, Shukurov A, Tuominen I
Publication type: Article
Publication status: Published
Journal: Astronomy and Astrophysics
Print publication date: 01/10/1999
ISSN (print): 0004-6361
ISSN (electronic): 1432-0746
Publisher: EDP Sciences