  Interferometric observations of the CO(1-0) line in the elliptical galaxy
NGC759 shows that it contains 2 10^9 Mo of molecular gas, confined to a
circumnuclear ring with an average radius of only 650pc. The maximum gas
surface density is 750 Mo/pc^2, which is comparable to the critical gas surface
density for large scale gravitational instabilities. The low CO(2-1)/CO(1-0)
ratio of 0.4 is consistent with a two-component molecular gas, consisting of a
cold and dense phase, containing most of the mass, and a warm and diffuse
component dominating the CO emission. We use a mass model for the underlying
galaxy which is applicable to spherical galaxies with an r^1/4 luminosity
profile. This leads to more modest estimates of the molecular gas fraction and
gas surface density then would have been derived using simpler models,
suggesting that many of the spectacular molecular gas properties of
ultraluminous FIR galaxies, which could be described by similar mass models,
may have to be revised. We discuss the possibility that NGC759 is in a late
stage of a merging between two gas-rich disk galaxies.
