We present the results of HI mapping with the NRAO The National Radio Astronomy Observatory is operated by Associated Universities , Inc. , under contract with the National Science Foundation . VLA of one of the most metal–deficient blue compact dwarf ( BCD ) galaxies known , SBS 0335–052 , with an oxygen abundance of only 1/40 that of the Sun .
We study the structure and dynamics of the neutral gas in this chemically young object with a spatial resolution of 20 \farcs 5 \times 15″ ( \sim 5.4 \times 3.9 kpc at an assumed distance of 54.3 Mpc ) , a sensitivity at the 2 \sigma detection level of \sim 2.0 K or 7.5 \times 10 ^ { 19 } cm ^ { -2 } and a velocity resolution of 21.2 km s ^ { -1 } .
We detected a large HI complex associated with this object with an overall size of about 66 by 22 kpc and elongated in the East–West direction .
There are two prominent , slightly resolved peaks visible in the integrated HI map , separated in the East–West direction by 22 kpc ( 84″ ) .
The eastern peak is nearly coincident with the position of the optical galaxy SBS 0335–052 .
The western peak is about a factor of 1.3 brighter in the HI line and is identified with a faint blue compact dwarf galaxy , SBS 0335–052W , with m _ { B } = 19.4 , and a metallicity close to the lowest values known for BCDs , about 1/50 that of the Sun .
The radial velocities of both systems are similar , suggesting that the two BCDs SBS 0335–052 and SBS 0335–052W constitute a pair of dwarf galaxies embedded in a common HI envelope .
Alternatively , the BCDs can be the nuclei of two distinct interacting primordial HI clouds .

The estimated total dynamical mass , assuming the BCDs form a bound system , is larger than \sim 6 \times 10 ^ { 9 } M _ { \odot } .
This is to be compared to a total gaseous mass M _ { gas } = 2.1 \times 10 ^ { 9 } M _ { \odot } , and a total stellar mass M _ { star } \leq 10 ^ { 8 } M _ { \odot } .
Hence , the mass of the SBS 0335–052 system is dominated by dark matter .
Because of the disturbed HI velocity field and the presence of what might be tidal tails at either end of the system , we favor the hypothesis of tidal triggering of the star formation in this system .
It can be due to either the nearby giant galaxy NGC 1376 or the mutual gravitational interaction of the two HI clouds .