The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). X. Hot Gas Reveals Deeply Embedded Star Formation
Artikel i vetenskaplig tidskrift, 2024
Massive infrared dark clouds (IRDCs) are considered to host the earliest stages of high-mass star formation. In particular, 70 μm dark IRDCs are the colder and more quiescent clouds. At a scale of about 5000 au using formaldehyde (H2CO) emission, we investigate the kinetic temperature of dense cores in 12 IRDCs obtained from the pilot Atacama Large Millimeter/submillimeter Array Survey of 70 μm dark High-mass clumps in Early Stages (ASHES). Compared to the 1.3 mm dust continuum and other molecular lines, such as C18O and deuterated species, we find that H2CO is mainly sensitive to low-velocity outflow components rather than to quiescent gas expected in the early phases of star formation. The kinetic temperatures of these components range from 26 to 300 K. The Mach number reaches about 15 with an average value of about 4, suggesting that the velocity distribution of gas traced by H2CO is significantly influenced by a supersonic nonthermal component. In addition, we detect warm line emission from HC3N and OCS in 14 protostellar cores, which requires high excitation temperatures (E u /k ∼ 100 K). These results show that some of the embedded cores in the ASHES fields are in an advanced evolutionary stage, previously unexpected for 70 μm dark IRDCs.
Författare
Natsuko Izumi
Academia Sinica
Patricio Sanhueza
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
M. M. Kettenis
Academia Sinica
X. Lu
Shanghai Astronomical Observatory
Shanghuo Li
Max-Planck-Gesellschaft
Giovanni Sabatini
Osservatorio Astrofisico di Arcetri
Fernando A. Olguin
National Tsing Hua University
Q. Zhang
Harvard-Smithsonian Center for Astrophysics
Fumitaka Nakamura
The Graduate University for Advanced Studies (SOKENDAI)
University of Tokyo
National Astronomical Observatory of Japan
Ken’ichi Tatematsu
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
Kaho Morii
National Astronomical Observatory of Japan
University of Tokyo
T. Sakai
University of Electro-Communications
Daniel Tafoya
Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 963 2 163Ämneskategorier
Meteorologi och atmosfärforskning
Astronomi, astrofysik och kosmologi
Atom- och molekylfysik och optik
Annan fysik
DOI
10.3847/1538-4357/ad18c6