Improved Searches for H I in Three Dwarf Spheroidal Galaxies

Previous searches for H I in our Galaxy's dwarf spheroidal companions have not been complete enough to settle the question of whether or not these galaxies have H I, especially in their outer parts. We present VLA observations of three dwarf spheroidals: Fornax, Leo II, and Draco, all of which have known stellar velocities. The new data show no H I emission or absorption. Column density limits in emission are 4x10^18 to 7x10^18 cm^-2 in the centers of the galaxies. The importance of the new observations is that they cover larger areas than previous searches and are less plagued by confusion with foreground (Galactic) H I. The apparent absence of neutral gas in the Fornax dwarf spheroidal is especially puzzling, because recent photometry shows evidence of stars only 10^8 years old. We discuss whether the VLA observations could have missed significant amounts of H I.