We present high-resolution HI 21 cm observations with the Karl G. Jansky Very Large Array (VLA) for three HI rich galaxies in absorption against radio quasars. Our sample contains six sightlines with impact parameters from 2.6 to 32.4 kpc. We detected a narrow HI absorber of FWHM 1.1 km/s at 444.5 km/s towards J122106.854+454852.16 probing the dwarf galaxy UCG 7408 at an impact parameter of 2.8 kpc. The absorption feature was barely resolved and its width corresponds to a maximum kinetic

more »

... ture, T_k ≈ 26 K. We estimate a limiting peak optical depth of 1.37 and a column density of 6× 10^19 cm^-2. The physical extent of the absorber is 0.04 kpc^2 and covers ∼25-30% of the background source. A comparison between the emission and absorption strengths suggests the cold-to-total HI column density in the absorber is 30 cold-to-total HI mass is 10 T_s∼ 1000 K) to cold phase ( T_s < 100 K) is suppressed in UGC 7408. The unusually low temperature of the HI absorber also indicates inefficiency in condensation of atomic gas into molecular gas. The suppression in condensation is likely to be the result of low-metal content in this galaxy. The same process might explain the low efficiency of star formation in dwarf galaxies despite their huge of gas reservoirs. We also report the non-detection of HI in absorption in five other sightlines. This indicates that either the cold gas distribution is highly patchy or the gas is much warmer ( T_s >1000 K) towards these sightlines.