THE VLA NASCENT DISK AND MULTIPLICITY SURVEY OF PERSEUS PROTOSTARS (VANDAM). II. MULTIPLICITY OF PROTOSTARS IN THE PERSEUS MOLECULAR CLOUD

摘要

We present a multiplicity study of all known protostars (94) in the Perseus molecular cloud from a Karl G. Jansky Very Large Array survey at Ka-band (8 mm and 1 cm) and C-band (4 and 6.6 cm). The observed sample has a bolometric luminosity range between 0.1?L⊙ and ~33?L⊙, with a median of 0.7?L⊙. This multiplicity study is based on the Ka-band data, having a best resolution of ~0065 (15 au) and separations out to ~43'' (10,000 au) can be probed. The overall multiplicity fraction (MF) is found to be 0.40?±?0.06 and the companion star fraction (CSF) is 0.71?±?0.06. The MF and CSF of the Class 0 protostars are 0.57?±?0.09 and 1.2?±?0.2, and the MF and CSF of Class I protostars are both 0.23?±?0.08. The distribution of companion separations appears bi-modal, with a peak at ~75 au and another peak at ~3000 au. Turbulent fragmentation is likely the dominant mechanism on 1000 au scales and disk fragmentation is likely to be the dominant mechanism on 200 au scales. Toward three Class 0 sources we find companions separated by 30 au. These systems have the smallest separations of currently known Class 0 protostellar binary systems. Moreover, these close systems are embedded within larger (50–400 au) structures and may be candidates for ongoing disk fragmentation.