The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). XI. Statistical Study of Early Fragmentation
Artikel i vetenskaplig tidskrift, 2024
Fragmentation during the early stages of high-mass star formation is crucial for understanding the formation of high-mass clusters. We investigated fragmentation within 39 high-mass star-forming clumps as part of the Atacama Large Millimeter/submillimeter Array Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES) survey. Considering projection effects, we have estimated core separations for 839 cores identified from the continuum emission and found mean values between 0.08 and 0.32 pc within each clump. We find compatibility of the observed core separations and masses with the thermal Jeans length and mass, respectively. We also present subclump structures revealed by the 7 m array continuum emission. Comparison of the Jeans parameters using clump and subclump densities with the separation and masses of gravitationally bound cores suggests that they can be explained by clump fragmentation, implying the simultaneous formation of subclumps and cores within rather than a step-by-step hierarchical fragmentation. The number of cores in each clump positively correlates with the clump surface density and the number expected from the thermal Jeans fragmentation. We also find that the higher the fraction of protostellar cores, the larger the dynamic range of the core mass, implying that the cores are growing in mass as the clump evolves. The ASHES sample exhibits various fragmentation patterns: aligned, scattered, clustered, and subclustered. Using the Q -parameter, which can help distinguish between centrally condensed and subclustered spatial core distributions, we finally find that in the early evolutionary stages of high-mass star formation, cores tend to follow a subclustered distribution.
Författare
Kaho Morii
National Astronomical Observatory of Japan
University of Tokyo
Patricio Sanhueza
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
Q. Zhang
Harvard-Smithsonian Center for Astrophysics
Fumitaka Nakamura
University of Tokyo
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
Shanghuo Li
Max-Planck-Gesellschaft
Giovanni Sabatini
Osservatorio Astrofisico di Arcetri
Fernando A. Olguin
National Tsing Hua University
H. Beuther
Max-Planck-Gesellschaft
Daniel Tafoya
Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium
Natsuko Izumi
Academia Sinica
Ken’ichi Tatematsu
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
T. Sakai
University of Electro-Communications
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 966 2 171Ämneskategorier
Meteorologi och atmosfärforskning
Astronomi, astrofysik och kosmologi
Sannolikhetsteori och statistik
Infrastruktur
Onsala rymdobservatorium
DOI
10.3847/1538-4357/ad32d0