Filament Intersections and Cold Dense Cores in Orion A North

TL;DR

This study uses high-resolution ALMA observations to analyze filament intersections and dense cores in Orion A North, revealing their distribution, physical properties, and gravitational stability, which informs star formation processes.

Contribution

It provides detailed insights into the spatial distribution, physical state, and gravitational stability of dense cores at filament intersections in Orion A North, highlighting their role in star formation.

Findings

Majority of dense cores are located around filament intersections.

Most cores are gravitationally bound but only a minority are collapsing.

Cores at intersections show higher column density and potential for star formation.

Abstract

We studied the filament structures and dense cores in OMC-2,3 region in Orion A North molecular cloud using the high-resolution N2H+ (1-0) spectral cube observed with the Atacama Large Millimeter/Submillimeter Array (ALMA). The filament network over a total length of 2 pc is found to contain 170 intersections and 128 candidate dense cores. The dense cores are all displaced from the infrared point sources (possible young stars), and the major fraction of cores (103) are located around the intersections. Towards the intersections, there is also an increasing trend for the total column density Ntot as well as the the power-law index of the column-density Probability Distribution Function (N-PDF), suggesting that the intersections would in general have more significant gas assembly than the other part of the filament paths. The virial analysis shows that the dense cores mostly have virial mass ratio of alpha_vir=M_vir/M_gas<1.0, suggesting them to be bounded by the self gravity. In the mean time, only about 23 percent of the cores have critical mass ratio of alpha_crit=M_crit/M_gas<1.0, suggesting them to be unstable against core collapse. Combining these results, it shows that the major fraction of the cold starless and possible prestellar cores in OMC-2,3 are being assembled around the intersections, and currently in a gravitationally bound state. But more extensive core collapse and star formation may still require continuous core-mass growth or other perturbatio