  We present Giant Meterwave Radio Telescope (GMRT) and Westerbork ynthesis
Radio Telescope (WSRT) observations of the recently discovered Local Group
dwarf galaxy, Leo T. The peak HI column density is measured to be 7x10^20
cm^-2, and the total HI mass is 2.8Xx10^5 Msun, based on a distance of 420 kpc.
Leo T has both cold (~ 500 K) and warm (~ 6000 K) HI at its core, with a global
velocity dispersion of 6.9 km/s, from which we derive a dynamical mass within
the HI radius of 3.3x10^6 Msun, and a mass-to-light ratio of greater than 50.
We calculate the Jeans mass from the radial profiles of the HI column density
and velocity dispersion, and predict that the gas should be globally stable
against star formation. This finding is inconsistent with the half light radius
of Leo T, which extends to 170 pc, and indicates that local conditions must
determine where star formation takes place. Leo T is not only the lowest
luminosity galaxy with on-going star formation discovered to date, it is also
the most dark matter dominated, gas-rich dwarf in the Local Group.
