New FUSE far-UV spectroscopy of the nearby metal-deficient ( Z _ { \odot } /8 ) cometary Blue Compact Dwarf ( BCD ) galaxy Markarian ( Mrk ) 59 is discussed .
The data are used to investigate element abundances in its interstellar medium .
The H i absorption lines are characterized by narrow cores which are interstellar in origin and by broad wings which are stellar in origin .
The mean interstellar H i column density is \sim 7 \times 10 ^ { 20 } cm ^ { -2 } in Mrk 59 .
No H _ { 2 } lines are seen and N ( H _ { 2 } ) is \lesssim 10 ^ { 15 } cm ^ { -2 } at the 10 \sigma level .
The lack of diffuse H _ { 2 } is due to the combined effect of a strong UV radiation field which destroys the H _ { 2 } molecules and a low metallicity which leads to a scarcity of dust grains necessary for H _ { 2 } formation .
P-Cygni profiles of the S vi 933.4 , 944.5 Å and O vi 1031.9 , 1037.6 Å lines are seen , indicating the presence of very hot O stars and a stellar wind terminal velocity of \sim 1000 km s ^ { -1 } .
By fitting the line profiles with multiple components having each a velocity dispersion b = 7 km s ^ { -1 } and spanning a radial velocity range of 100 km s ^ { -1 } , some of which can be saturated , we derive heavy element abundances in the neutral gas .
We find log N ( O i ) / N ( H i ) = –5.0 \pm 0.3 or [ O i /H i ] = –1.5 for the neutral gas , about a factor of 10 below the oxygen abundance of the supergiant H ii region , implying self-enrichment of the latter .