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The effective stability parameter for two-component galactic discs: is 1/Q ~ 1/Q_stars + 1/Q_gas ?

Alessandro Romeo (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; Joachim Wiegert (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik)
Monthly notices of the Royal Astronomical Society (0035-8711). Vol. 416 (2011), 2, p. 1191-1196.
[Artikel, refereegranskad vetenskaplig]

The Wang-Silk approximation, Q-1≈Q-1stars+Q-1gas, is frequently used for estimating the effective Q parameter in two-component discs of stars and gas. Here we analyse this approximation in detail, and show how its accuracy depends on the radial velocity dispersions and Toomre parameters of the two components. We then propose a much more accurate but still simple approximation for the effective Q parameter, which further takes into account the stabilizing effect of disc thickness. Our effective Q parameter is a natural generalization of Toomre's Q, and as such can be used in a wide variety of contexts, e.g. for predicting star formation thresholds in galaxies or for measuring the stability level of galactic discs at low and high redshifts.

Denna post skapades 2011-09-02. Senast ändrad 2015-04-08.
CPL Pubid: 145722


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