Observations of Water Masers in the NGC 1333 IRAS 4 Region

The NGC 1333 IRAS 4 region was observed in the 22 GHz H2O maser line with an angular resolution of about 0.08 arcseconds. Two groups of masers were detected, one near IRAS 4A and the other near BI. Among the eight maser spots detected near IRAS 4A, six spots are located close to A2, within 100 AU, and the maser velocities are also near the systemic velocity of the cloud core. These masers are probably related with the circumstellar disk. Since there is no maser spot detected around A1, the star forming process is relatively more active in A2 than in A1. Four maser spots were detected near IRAS 4BI. Since most of them are distributed along a straight line in the direction of the outflow, BI masers are most likely related with the jet or outflow. The disk-outflow dichotomy of H2O masers is discussed briefly. No maser was detected near H2O(C), another maser source reported previously.