Growth time of acoustic perturbations in isentropically unstable heat-releasing medium

D. S. Riashchikov   ; I. A. Pomelnikov   ; N. E. Molevich

Vestnik Samarskogo universiteta. Estestvennonaučnaâ seriâ, Tome 28 (2022) no. 1-2, pp. 113-119

Résumé

Isentropic instability is a type of thermal instability that leads to the growth of acoustic waves. As a result of wave growth in such media, autowave structures are formed, the parameters of which depend only on the properties of the medium and can be predicted both analytically and numerically. This study aims to answer the question of how quickly these structures can form in an isentropically unstable medium with parameters similar to Orion Bar. It is shown that the growth time depends on the characteristic size of the initial perturbation. The fastest growing structures take 3-6 thousand years to reach half their maximum amplitude. Further growth to the maximum value takes 15-20 thousand years.

Détail

Keywords: instability, thermal instability, nonlinear waves, shock waves, autowaves, interstellar gas
Mots-clés : photodissociation region, Orion Bar.

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