A kinematic analysis of the CO clouds toward a reflection nebula NGC 2023 observed using the Nobeyama 45 m telescope: Further evidence for a cloud–cloud collision in the Orion region

Abstract We performed fully sampled J = 1–0 line observations of 12CO and 13CO toward the reflection nebula NGC 2023 using Nobeyama 45 m telescope. It covered entire region with angular velocity resolutions 19″ corresponding to 0.04 pc 0.33 km s−1, respectively. analyzed data focusing on gas dynamics revealed two components, each a mass $\sim\! 3000 \mbox{$\, {M}_\odot $}$, at radial velocities 10 12 s−1. These components show spatially complementary distributions are connected in velocity, both which typical signatures cloud–cloud collision (CCC). Although previous studies favored scheme triggering by H ii IC 434, our results that effect is limited only surface molecular cloud, does not contribute compression overall star formation. Comparing present those for neighboring 2024, we find their active formation can be explained single CCC event. suggest s−1 clouds collided ∼0.4 Myr ago, common regions, but triggered B1.5V-type HD 37903 as well ∼20 low-mass stars 2023, OB 2024. The column density three times lower than may result different activity suggested trend ∼50 other CCC-triggered star-forming regions literature.