A STUDY OF THE UNUSUAL STARBURST GALAXY MARKARIAN 603 (=NGC 1222)

We present a detailed morphological and spectral investigation of the unusual starburst galaxy Markarian 603 = NGC 1222. Markarian 603 with its two companions forms a triple system. The main component of the tr iplet, Markarian 603, looks like a nE type galaxy, the other two are l ow-luminosity, high-surface brightness compact objects. Markarian 603 has a starburst nucleus in which the emitting gas is photoionized by a bout 3 10(5) OB stars. Star formation occurs also in the host galaxy o f the Markarian object whose rate is about four times smaller than tha t observed in the nuclear region. Both companions of Markarian 603, in spite of their large similarity with BCDGs, are more evolved than the latter.