2023/09/23 by L. K. Dewangan, A. K. Maity, Dewangan, L. K. +11
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2309.13351
openalex publication_date 2023/09/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We report the discovery of intertwined/entangled sub-structures towards the bubble wall of NGC 3324 below a physical scale of 4500 AU, which is the sharp edge/ionization front/elongated structure traced at the interface between the HII region and the molecular cloud. The sharp edge appears wavy in the Spitzer 3.6-8.0 μm images (resolution ∼2''). Star formation signatures have mostly been traced on one side of the ionization front, which lies on the molecular cloud's boundary. The James Webb Space Telescope's (JWST) near- and mid-infrared images (resolution ∼0.07''-0.7'') are employed to resolve the sharp edge, which has a curvature facing the exciting O-type stars. The elongated structures are associated with the 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission, the 4.05 μm ionized emission, and the 4.693 μm H2 emission. However, the PAH-emitting structures are depicted between the other two. The H2 emission reveals numerous intertwined sub-structures which are not prominently traced in the 3.3 μm PAH emission. The separation between two sub-structures in the H2 emission is ∼1.1'' or 2420 AU. The intertwined sub-structures are traced in the spatial areas associated with the neutral to H2 transition zone, suggesting the origin of these structures by ``thin-shell'' instability. Furthermore, an arc-like feature traced in the Spitzer 3.6-8.0 μm images is investigated as a bipolar HII region (extent ∼0.35 pc) at Td ∼25-28~K using the JWST images. A massive star candidate VPHAS-OB1 #03518 seems to be responsible for the bipolar HII region.