Dr. Cheng-Han Hsieh

Yale University, USA

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

Abstract: Angular momentum is one of the most important physical quantities that govern star formation. The initial angular momentum of cores may be responsible for its fragmentation and can influence 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. Our high-resolution N2D+ ALMA observations of the LBS23 (HH24-HH26) region in Orion B shows a rotating filament with a total specific angular momentum (4 x10^20 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} ~ 0.04) are comparable to those observed in rotating cores with sizes similar to our filament width (~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 filament and cores develop simultaneously due to multi-scale growth of nonlinear perturbation generated by turbulence.