Analyzing Spectral Lines of Nearby Extreme Galaxies

Chemical Abundances and Electron densities were calculated for two galaxies IC 1809 and UGC 02172 categorized as extreme star-forming systems from high H-alpha equivalent of -82 and -125, respectively. Line ratios [NII] λ6583/[OII] λ3727 were used to determine the metallicity for IC 1809 yielding a measurement of Z = 1.3 ± 0.1υ , where ionization did not display a significant effect. However, for UGC 02172 the line ratios ([O II] λ3727 + [O III] λλ4959, 5007)/Hβ , and [O III] λ5007 / [O II] λ3727, [N II] λ6583/[Hα] had to be used in an iterative process to determine the metallicity. UGC 02172 is a metal poor galaxy with Z = 0.3 ± 0.1υ , and low reddening E(B-V) ≈ 0.906. These galaxies are evaluated in the context of establishing their star formation rates and how their characteristics can be used to study the star formation history of the early universe.