Mechanisms of Dense Cores Fragmentation and Multiple System Formation in Orion A

ABSTRACT :
When dense cores in molecular clouds or filamentary structures collapse, they may undergo fragmentation and form binary or multiple systems. Recent high-resolution surveys at (sub-)millimeter wavelengths have revealed that approximately half of protostars exist in binary or multiple systems. Thus, it is important to understand the fragmentation process. In this study, we investigate the key mechanisms driving fragmentation by comparing the physical conditions of fragmented and unfragmented dense cores in Orion A. Utilizing the archival submillimeter continuum data from the JCMT and the ALMA high-resolution (0'.08) survey of Class 0 and I protostars, we identify 41 dense cores hosting single protostar and 16 cores hosting binary or multiple systems in Orion A. We find that the dense cores hosting binary/multiple systems exhibit significantly higher mass density and Mach number than those hosting single protostars, while there are no correlations between the energies ratios of turbulence and magnetic field to gravity in the dense cores with fragmentation. Our results suggest that dense cores with a higher density, which is possibly induced by their supersonic turbulence and can lead to local collapse, are prone to fragmentation and form binary/multiple systems, while the magnetic field has limited influence on fragmentation in Orion A.