Symmetry properties and widths of the filamentary structures in the Orion A giant molecular cloud

TL;DR

This study analyzes the symmetry and widths of 225 filaments in the Orion A molecular cloud, revealing that most are asymmetrical and measuring their typical widths using different fitting methods, with implications for star formation.

Contribution

It provides a detailed analysis of filament symmetry properties and width measurements in Orion A using CO observations, which is novel in its large sample and comprehensive profile analysis.

Findings

65.3% of filament segments are intrinsically asymmetrical.

Typical FWHM widths are ~0.67 pc (Plummer) and ~0.50 pc (Gaussian).

Strong association between filaments and YSOs.

Abstract

We identify 225 filaments from an H$_2$ column density map constructed using simultaneous $^{12}$CO, $^{13}$CO, and C$^{18}$O (J=1-0) observations carried out as a part of the MWISP project. We select 46 long filaments with lengths above 1.2 pc to analyze the filament column density profiles. We divide the selected filaments into 397 segments and calculate the column density profiles for each segment. The symmetries of the profiles are investigated. The proportion of intrinsically asymmetrical segments is 65.3$\%$, and that of intrinsically symmetrical ones is 21.4$\%$. The typical full width at half maximum (FWHM) of the intrinsically symmetrical filament segments is $\sim$ 0.67 pc with the Plummer-like fitting, and $\sim$ 0.50 pc with the Gaussian fitting, respectively. The median FWHM widths derived from the second-moment method for intrinsically symmetrical and asymmetrical profiles are $\sim$ 0.44 and 0.46 pc, respectively. Close association exists between the filamentary structures and the YSOs in the region.