2008/05/12 by M. S. Kirsanova, A. M. Sobolev, А. М. Соболев +4
Chemical Engineering · Physics and Astronomy · #Advanced Combustion Engine Technologies #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Biology #Molecular cloud #Physics #Spatial distribution #Star formation #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2008.13429.x
Accepted by MNRAS, 10 pages, 5 figures, 2 tables
arxiv created 2008/05/12 · openalex publication_date 2008/06/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a picture of star formation around the H ii region Sh2-235 (S235) based upon data on the spatial distribution of young stellar clusters and the distribution and kinematics of molecular gas around S235. We observed 13CO (1–0) and CS (2–1) emission toward S235 with the Onsala Space Observatory 20-m telescope and analysed the star density distribution with archival data from the Two Micron All-Sky Survey (2MASS). Dense molecular gas forms a shell-like structure at the southeastern part of S235. The young clusters found with 2MASS data are embedded in this shell. The positional relationship of the clusters, the molecular shell and the H ii region indicates that expansion of S235 is responsible for the formation of the clusters. The gas distribution in the S235 molecular complex is clumpy, which hampers interpretation exclusively on the basis of the morphology of the star-forming region. We use data on kinematics of molecular gas to support the hypothesis of induced star formation, and distinguish three basic types of molecular gas components. The first type is primordial undisturbed gas of the giant molecular cloud, the second type is gas entrained in motion by expansion of the H ii region (this is where the embedded clusters were formed) and the third type is a fast-moving gas, which might have been accelerated by winds from the newly formed clusters. The clumpy distribution of molecular gas and its kinematics around the H ii region implies that the picture of triggered star formation around S235 can be a mixture of at least two possibilities: the ‘collect-and-collapse’ scenario and the compression of pre-existing dense clumps by the shock wave.