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

TL;DR

This study identifies key physical conditions, such as higher density and turbulence, that influence fragmentation and multiplicity in dense cores of Orion A, providing insights into star formation processes.

Contribution

It compares physical conditions of fragmented and unfragmented dense cores in Orion A, highlighting the roles of density and turbulence in core fragmentation.

Findings

Fragmented cores have higher density and Mach number.

Magnetic fields show limited influence on fragmentation.

No correlation between energy ratios and fragmentation occurrence.

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 investigated 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 a 0.''1 resolution, we identified 38 dense cores hosting single protostars and 15 cores hosting binary or multiple systems. We measured the dense cores properties with the Herschel dust temperature, Nobeyama 45m N$_2$H$^+$ J=1-0, and JCMT polarization data. Our results reveal that the dense cores hosting binary/multiple systems exhibit significantly higher density and Mach number 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 the 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.