出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We conducted a study of water masers at 22.2 GHz around the Class 0 protostars called A and B
in the NGC1333-IRAS 4 star forming region. Using the VLBA, we observed water emission at
milliarcsecond scale and in phase referencing over four epochs spaced by one month to measure
proper motions. The observations confirmed the high variability of H2O maser emission, shorter
than one month. The high angular resolution allowed us to show that A2, the weakest source
of the IRAS 4A binary system, is associated with water masers. On the other hand, the spots
associated with IRAS 4B show a high degree of collimation down to 25 AU and they are probably
tracing the protostellar jet producing a bipolar molecular outflow.
