Article

Mass-to-light ratio of elliptical galaxies

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Abstract

Two virial formulas, which take into account the observed flattening, are established for oblate ellipticals obeying the r to the 1/4th power law and used to derive the mean mass to light ratios in their central part. One of them, which requires the knowledge of only one kinematical parameter, the central (stellar) velocity dispersion, is applied to 197 ellipticals. The other one, which uses in addition the maximum stellar rotation velocity, is shown to be less sensitive to the unknown true flattenings and to possible velocity anisotropies. It is applied to 30 ellipticals. Both methods give a mean blue mass to luminosity ratio of about 13, without any clear correlation with the absolute luminosity of the galaxy.

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