Key Physical Parameters Influencing Fragmentation and Multiplicity in Dense Cores of Orion A

Abstract When dense cores in molecular clouds or filamentary structures collapse and form protostars, they may undergo fragmentation and form binary or multiple systems. In this paper, we investigate the key mechanisms influencing fragmentation, by comparing the physical conditions of fragmented and unfragmented dense cores (∼0.1 pc) in Orion A. Utilizing archival submillimeter continuum data from the James Clerk Maxwell Telescope (JCMT) and the Atacama Large Millimeter/submillimeter Array survey of Class 0 and I protostars at 0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>.</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>″</mml:mi> </mml:mrow> </mml:mover> </mml:math> 1 resolution, we identified 38 dense cores hosting single protostars and 15 cores hosting binary or multiple systems. We measured the dense core properties using Herschel dust temperature, Nobeyama 45 m N 2 H + J = 1−0, and JCMT polarization data. Our results reveal that the dense cores hosting binary/multiple systems exhibit significantly higher densities and Mach numbers compared to those hosting single protostars, while there are no correlations between the occurrence of fragmentation and the energy ratios of turbulence and magnetic field to gravity. Our results suggest that the higher density and supersonic turbulence of dense cores can lead to local collapse and fragmentation, to form binary/multiple systems, while the magnetic field has limited influence on fragmentation in the dense cores in Orion A.