On the mass and density of the stellar disk of M33 |
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| Authors: | A S Saburova A V Zasov |
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| Institution: | 1.Sternberg Astronomical Institute of Moscow State University,Moscow,Russia |
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| Abstract: | The disk surface density of the nearby spiral galaxy M33 is estimated assuming that it is marginally stable against gravitational
perturbations. For this purpose we used the radial profile of line-of-sight velocity dispersion of the disk planetary nebulae
obtained by Ciardullo et al. (2004). The surface density profile we obtained is characterized by the radial scalelength which
is close to the photometrical one and is in a good agreement with the rotation curve of M33 and with the mass-to-light ratio
which follows from the stellar population model. However at the galactocentric distance r > 7 kpc the dynamical overheating of the disk remains quite possible. The thickness of the stellar disk of M33 should increase
outwards from the center. The dark halo to total mass ratio is estimated as a function of r. The effective oxygen yield obtained in the frame of instantaneous recycling approximation using the disk surface density
and the observed gradient of O/H increases with radius. It may indicate that the role of accretion of metalpoor gas in the
chemical evolution of interstellar medium decreases outwards. |
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