The Wisconsin H \alpha Mapper has been used to set the first deep upper limits on the intensity of diffuse H \alpha emission from warm ionized gas in the Draco and Ursa Minor dwarf spheroidal galaxies .
Assuming a velocity dispersion of 15 km s ^ { -1 } for the ionized gas , we set limits of I _ { H \alpha } \leq 0.024 R and I _ { H \alpha } \leq 0.021 R for the Draco and Ursa Minor dSphs , respectively , averaged over our 1 ^ { \circ } circular beam .
Adopting a simple model for the ionized interstellar medium , these limits translate to upper bounds on the mass of ionized gas of \lesssim 10 % of the stellar mass , or \sim 10 times the upper limits for the mass of neutral hydrogen .
Note that the Draco and Ursa Minor dSphs could contain substantial amounts of interstellar gas , equivalent to all of the gas injected by dying stars since the end of their main star forming episodes \gtrsim 8 Gyr in the past , without violating these limits on the mass of ionized gas .