Year: 2018
Type: article
Abstract: We report results of the observations of 15 regions in several molecular lines for a statistical study of massive cluster-forming clumps. We identified 24 clumps based on the C18O (J = 1–0) data obtained by the NRO 45 m telescope, and found that 16 of them are associated with young clusters. The clumps associated with clusters have a typical mass, radius, and molecular density of ∼1 × 103M☉, ∼0.5 pc, ∼1 × 105cm−3, respectively. We categorized the clumps and clusters into four types according to the spatial coincidence of gas and star density, and discussed their evolutions: Clumps without clusters (Type 1), clumps showing good correlations with clusters (Type 2), clumps showing poor correlations with clusters (Type 3), and clusters with no associated clumps (Type 4). Analyses of the velocity structures and the chemical compositions imply that the clump + cluster systems should evolve from Type 1 to Type 4. We found that some of the Type 2 clumps are infalling on the clump-scale to form clusters at the clump center, which should commonly occur in the beginning of cluster formation. Interestingly, all of the identified Type 1 clumps are likely to be older than the Type 2 clumps in terms of chemical compositions, suggesting that they have been gravitationally stable for a long time, possibly being supported by the strong magnetic field of ≳1 mG. Type 1 clumps younger than the observed Type 2 clumps should be very rare to find because of their short lifetime.
Source: The Astrophysical Journal
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: Understanding the Initial Structures of Cluster Forming Clumps, Revealing the origin of dark gas around molecular clouds using the velocity-dispersion method, International joint research for maser variability and mass accretion processes in high-mass protostars, Challenge to detect the greenhouse effect for science education, Search in the Universe for Seed Materials towards Life: Interdisciplinary Research between Astronomy and Spectroscopy, A numerical study of circumstellar structures around binary protostars with adaptive mesh refinement, Development of science teaching program for university students at Faculty of Education, G8157362042, A Thorough Understanding of Role of Magnetic Field in Star Formation Process by CCS/SO Zeeman Observations
OpenAlex ID: W2787216400