Spectroscopic properties of our sample of intense emission line objects. From left to right panels: distribution of the Balmer decrement derived extinction parameter, distribution of the equivalent width of Hβ, distribution of Hβ luminosity, and distribution of the oxygen abundance derived from the direct method for objects with the auroral [O III]λ4363 Å line detected. This line is detected virtually in all our galaxies and allows the determination of the electron temperature (see text).