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 2 148

Subject Categories

Meteorology and Atmospheric Sciences

Astronomy, Astrophysics and Cosmology

Probability Theory and Statistics

DOI

10.3847/1538-4357/acccea

More information

Latest update

7/7/2023 1