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Description
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_{sun}_ and ~33 L_{sun}_, with a median of 0.7 L_{sun}_. This multiplicity study is based on the Ka-band data, having a best resolution of ~0.065" (15 au) and separations out to ~43" (10000 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.
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