UCM1612- A NEWLY IDENTIFIED BLUE COMPACT GALAXY(1308 )

UCM1612+1308 is a new emission-line galaxy iden tified in the context of the Universidad Complutense de Madrid (UCM) survey. This object was classified as Blue Compact Galaxy (BCG) from photometric data. A deta iled spectroscopic study from new optical observations is presented no w. The physical conditions and chemical composition are derived. The i onic abundances yield to a metallicity of 0.23 +/- 0.01 Z(.) and a ver y low nitrogen to oxygen abundances ratio, log(N/O) = -1.74 +/- 0.07, supporting a primary nucleosynthesis origin for the nitrogen. The same value has been obtained for the sulfur to oxygen ratio. The compariso n of the helium abundance with the oxygen and nitrogen abundances evid ences a quickly enrichment of oxygen produced by massive stars. The io nizing cluster has been analyzed yielding a relatively low ionization parameter, log (U) over bar = -3, total number of stars, log N = 6.18 , stellar mass, log M = 5.71 M-., and gas mass log M-g = 7.42 M-. A l ower limit of the dust mass, log M-dust = 5.65 M-., has been obtained from the IRAS fluxes. The observed data and derived parameters, when i nterpreted with the evolutionary synthesis models by Leitherer & Heckm an (1995), point out to an instantaneous burst with an age of log t = 6.7 yr.