The ALMA Survey of 70 mu m Dark High-mass Clumps in Early Stages (ASHES). IX. Physical Properties and Spatial Distribution of Cores in IRDCs
Journal article, 2023
The initial conditions found in infrared dark clouds (IRDCs) provide insights on how high-mass stars and stellar clusters form. We have conducted high-angular resolution and high-sensitivity observations toward thirty-nine massive IRDC clumps, which have been mosaicked using the 12 and 7 m arrays from the Atacama Large Millimeter/submillimeter Array. The targets are 70 mu m dark massive (220-4900 M (circle dot)), dense (>10(4) cm(-3)), and cold (similar to 10-20 K) clumps located at distances between 2 and 6 kpc. We identify an unprecedented number of 839 cores, with masses between 0.05 and 81 M (circle dot) using 1.3 mm dust continuum emission. About 55% of the cores are low-mass (M (circle dot)), whereas less than or similar to 1% (7/839) are high-mass (greater than or similar to 27 M (circle dot)). We detect no high-mass prestellar cores. The most massive cores (MMC) identified within individual clumps lack sufficient mass to form high-mass stars without additional mass feeding. We find that the mass of the MMCs is correlated with the clump surface density, implying denser clumps produce more massive cores. There is no significant mass segregation except for a few tentative detections. In contrast, most clumps show segregation once the clump density is considered instead of mass. Although the dust continuum emission resolves clumps in a network of filaments, some of which consist of hub-filament systems, the majority of the MMCs are not found in the hubs. Our analysis shows that high-mass cores and MMCs have no preferred location with respect to low-mass cores at the earliest stages of high-mass star formation.
Author
Kaho Morii
University of Tokyo
National Institutes of Natural Sciences
Patricio Sanhueza
National Institutes of Natural Sciences
The Graduate University for Advanced Studies (SOKENDAI)
Fumitaka Nakamura
University of Tokyo
The Graduate University for Advanced Studies (SOKENDAI)
National Institutes of Natural Sciences
Qizhou Zhang
Harvard-Smithsonian Center for Astrophysics
Giovanni Sabatini
Italian ALMA Regional Centre
Istituto nazionale di astrofisica (INAF)
Henrik Beuther
Max Planck Society
Xing Lu
Chinese Academy of Sciences
Shanghuo Li
Max Planck Society
Guido Garay
University of Chile (UCH)
James M. Jackson
Green Bank Observatory
Fernando A. Olguin
National Tsing Hua University
Daniel Tafoya
Chalmers, Space, Earth and Environment, Onsala Space Observatory
Ken'ichi Tatematsu
National Institutes of Natural Sciences
The Graduate University for Advanced Studies (SOKENDAI)
Natsuko Izumi
Academia Sinica
Takeshi Sakai
University of Electro-Communications
Andrea Silva
National Institutes of Natural Sciences
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 950 2 148Subject Categories
Meteorology and Atmospheric Sciences
Astronomy, Astrophysics and Cosmology
Probability Theory and Statistics
DOI
10.3847/1538-4357/acccea