2020/04/30 by Xuefang Xu, Xuefang 雪芳 Xu 徐, Di 菂 Li 李 +6 · 1 citation
Physics and Astronomy · #Angular momentum #Angular velocity #Astro and Planetary Science #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Core (optical fiber) #Elongation #Molecular cloud #Perpendicular #Rotation (mathematics) #Rotational energy #Telescope #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.3847/2041-8213/ab8ad7
published as The Astrophysical Journal Letters, 2020, Volume 894, Number 2
openalex publication_date 2020/05/01 · openalex created_date 2020/05/13 · arxiv created 2021/11/04 · arxiv updated 2021/11/05 · openalex updated_date 2026/08/05
Abstract We present high-angular-resolution Atacama Large Millimeter/submillimeter Array images of N 2 H + (1–0) that have been combined with those from the Nobeyama telescope toward the Orion Molecular Cloud (OMC)-2 and OMC-3 filamentary regions. The filaments (with typical widths of ∼0.1 pc) and dense cores are resolved. The measured 2D velocity gradients of cores are between 1.3 and 16.7 km s −1 pc −1 , corresponding to a specific angular momentum ( J / M ) between 0.0012 and 0.016 pc km s −1 . With respect to the core size R , the specific angular momentum follows a power law J / M ∝ R 1.52±0.14 . The ratio ( β ) between the rotational energy and gravitational energy ranges from 0.00041 to 0.094, indicating insignificant support from rotation against gravitational collapse. We further focus on the alignment between the cores’ rotational axes, which is defined to be perpendicular to the direction of the velocity gradient ( θ G ), and the direction of elongation of filaments ( θ f ) in this massive star-forming region. The distribution of the angle between θ f and θ G was found to be random, i.e., the cores’ rotational axes have no discernible correlation with the elongation of their hosting filament. This implies that, in terms of angular momentum, the cores have evolved to be dynamically independent from their natal filaments.