期刊
ASTRONOMY REPORTS
卷 52, 期 4, 页码 257-269出版社
MAIK NAUKA/INTERPERIODICA/SPRINGER
DOI: 10.1134/S106377290804001X
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The equilibrium thickness of the isothermal layers of interstellar gas and volume gas densities in the plane of the disk as a function of galactocentric distance R are computed for seven spiral galaxies (including the Milky Way) using an axisymmetrical model. In this model, the thickness of the stellar disk varies with R and remains approximately equal to the minimum thickness of a stable equilibrium disk. We found the disk thickness to increase toward the periphery in at least five of the seven galaxies. The density of the stellar disk decreases with R faster than rho(gas), so that gas dominates at the disk peripheries in terms of density. A comparison of the azimuthally averaged star formation rate SFR and the gas density shows the absence of a universal Schmidt law SFR similar to rho(n)(gas) for galaxies. However, the SFRs in various galaxies are better correlated with the volume than the gas surface density. The parameter n in the Schmidt law formally calculated using the least-squares method ties in the interval 0.8-2.4, being, on average, close to 1.5. The values of n calculated separately for the molecular gas display substantial scatter, but are, on average, close to unity. The value of n appears to increase with decreasing rho(gas) so that the fraction of gas that actively participates in star formation decreases with n.
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