Rotating filament in Orion B: Do cores inherit their angular momentum from their parent filament?

TL;DR

This study measures the specific angular momentum of a star-forming filament in Orion B using ALMA observations, revealing how filament rotation may influence core formation and angular momentum inheritance.

Contribution

It provides one of the first reliable observational measurements of filament angular momentum and compares it with theoretical models and core properties.

Findings

Specific angular momentum is $4 imes 10^{20} cm^2s^{-1}$.

Angular momentum scales with radius as j(r) ∝ r^{1.83}.

Rotational energy is about 4% of gravitational energy.

Abstract

Angular momentum is one of the most important physical quantities that govern star formation. The initial angular momentum of a core may be responsible for its fragmentation and can have an influence on the size of the protoplanetary disk. To understand how cores obtain their initial angular momentum, it is important to study the angular momentum of filaments where they form. While theoretical studies on filament rotation have been explored, there exist very few observational measurements of the specific angular momentum in star-forming filaments. We present high-resolution N2D+ ALMA observations of the LBS 23 (HH24-HH26) region in Orion B, which provide one of the most reliable measurements of the specific angular momentum in a star-forming filament. We find the total specific angular momentum ($4 \times 10^{20} cm^2s^{-1}$), the dependence of the specific angular momentum with radius (j(r) $\propto r^{1.83}$), and the ratio of rotational energy to gravitational energy ($\beta_{rot} \sim 0.04$) comparable to those observed in rotating cores with sizes similar to our filament width ($\sim$ 0.04 pc) in other star-forming regions. Our filament angular momentum profile is consistent with rotation acquired from ambient turbulence and with simulations that show cores and their host filaments develop simultaneously due to the multi-scale growth of nonlinear perturbation generated by turbulence.