We compare the gas distribution , kinematics and the current star formation in a sample of 10 very faint ( -13.37 < { M _ { B } } < -9.55 ) dwarf galaxies .
For 5 of these galaxies we present fresh , high sensitivity , GMRT HI 21cm observations .
We find that the large scale HI distribution in the galaxies is typically irregular and clumpy , with the peak gas density rarely occurring at the geometric center .
We also find that the velocity fields for all the galaxies have an ordered component , although in general , the patterns seen do not fit that expected from a rotating disk .
For all our galaxies we construct maps of the HI column density at a constant linear resolution of \sim 300 pc ; this forms an excellent data set to check for the presence of a threshold column density for star formation .
We find that while current star formation ( as traced by H \alpha emission ) is confined to regions with relatively large ( N _ { HI } > ( 0.4 - 1.7 ) ~ { } \times~ { } 10 ^ { 21 } cm ^ { -2 } ) HI column density , the morphology of the H \alpha emission is in general not correlated with that of the high HI column density gas .
Thus , while high column density gas may be necessary for star formation , in this sample at least , it is not sufficient to ensure that star formation does in fact occur .
We examine the line profiles of the HI emission , but do not find a simple relation between regions with complex line profiles and those with on-going star formation .
Our sample includes examples of regions where there is on-going star formation , but the profiles are well fit by a single Gaussian , as well as regions where there is no star formation but the line profiles are complex .
Finally , we examine the very fine scale ( \sim 20 - 100 pc ) distribution of the HI gas , and find that at these scales the emission exhibits a variety of shell like , clumpy and filamentary features .
The H \alpha emission is sometimes associated with high density HI clumps , sometimes the H \alpha emission lies inside a high density shell , and sometimes there is no correspondence between the H \alpha emission and the HI clumps .
In summary , the interplay between star formation and gas density in these galaxy does not seem to show the simple large scale patterns observed in brighter galaxies .