2026/02/28 by Kazuki Tokuda, Mitsuki Omura, Naoto Harada +9 · 1 voice
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Astrophysics and Star Formation Studies #Fullerene Chemistry and Applications
paper · doi:10.3847/2041-8213/ae47ec
openalex created_date 2026/02/18 · openalex publication_date 2026/04/02 · openalex updated_date 2026/07/28
Abstract Infall and outflows, coupled with magnetic fields, rapidly structure the gas around newborn protostars. Shocks from interacting components encode the temperature and density distribution, offering a direct probe of the earliest evolution history. However, interferometric observations characterizing warm envelopes using high-excitation lines remain scarce. We present Atacama Large Millimeter/submillimeter Array Band 9 observations of the Taurus dense core MC 27/L1521F, which hosts a Class 0 protostar, targeting the CO( J = 6–5) line at an angular resolution of ∼2″ (≈300 au). We detect an off-centered ringlike structure with a diameter of ∼1000 au that was not identifiable in previous low- J CO data, where emission close to the systemic velocity is strongly affected by optical depth. The ring shows a typical peak brightness temperature of ∼3 K at our resolution. Excitation considerations indicate that the detected CO( J = 6–5) emission likely arises from relatively warm ( T ≳ 20 K) and dense ( n (H 2 ) ≳ 10 5 cm −3 ) gas embedded within the surrounding cold, dense core. The morphology and kinematics suggest an energetic and localized shock-heating event, potentially linked to dynamical gas–magnetic-field interactions in the earliest protostellar phase. Our results demonstrate that high- J CO observations provide a powerful new window on warm and dense gas components, enabling a more direct view of the physical processes operating at the onset of star formation.