The ALMA Survey of 70 mu m Dark High-mass Clumps in Early Stages (ASHES). II. Molecular Outflows in the Extreme Early Stages of Protocluster Formation
Artikel i vetenskaplig tidskrift, 2020

We present a study of outflows at extremely early stages of high-mass star formation obtained from the ALMA Survey of 70 mu m dark High-mass clumps in Early Stages (ASHES). Twelve massive 3.6-70 mu m dark prestellar clump candidates were observed with the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 6. Forty-three outflows are identified toward 41 out of 301 dense cores using the CO and SiO emission lines, yielding a detection rate of 14%. We discover six episodic molecular outflows associated with low- to high-mass cores, indicating that episodic outflows (and therefore episodic accretion) begin at extremely early stages of protostellar evolution for a range of core masses. The time span between consecutive ejection events is much smaller than those found in more evolved stages, which indicates that the ejection episodicity timescale is likely not constant over time. The estimated outflow dynamical timescale appears to increase with core masses, which likely indicates that more massive cores have longer accretion timescales than less massive cores. The lower accretion rates in these 70 mu m dark objects compared to the more evolved protostars indicate that the accretion rates increase with time. The total outflow energy rate is smaller than the turbulent energy dissipation rate, which suggests that outflow-induced turbulence cannot sustain the internal clump turbulence at the current epoch. We often detect thermal SiO emission within these 70 mu m dark clumps that is unrelated to CO outflows. This SiO emission could be produced by collisions, intersection flows, undetected protostars, or other motions.

Massive stars

Protoclusters

Protostars

Star formation

Infrared dark clouds

Interstellar line emission

Interstellar medium

Stellar jets

Stellar winds

Författare

Shanghuo Li

Chinese Academy of Sciences

Korea Astronomy and Space Science Institute

Harvard-Smithsonian Center for Astrophysics

Patricio Sanhueza

National Institutes of Natural Sciences

The Graduate University for Advanced Studies (SOKENDAI)

Qizhou Zhang

Harvard-Smithsonian Center for Astrophysics

Fumitaka Nakamura

The Graduate University for Advanced Studies (SOKENDAI)

National Institutes of Natural Sciences

Xing Lu

National Institutes of Natural Sciences

Junzhi Wang

Chinese Academy of Sciences

Tie Liu

Chinese Academy of Sciences

Ken'ichi Tatematsu

National Institutes of Natural Sciences

James M. Jackson

NASA Ames Research Center

Andrea Silva

National Institutes of Natural Sciences

Andres E. Guzman

National Institutes of Natural Sciences

Takeshi Sakai

University of Electro-Communications

Natsuko Izumi

National Institutes of Natural Sciences

Ibaraki University

Daniel Tafoya

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium, Observationssupport

Fei Li

Chinese Academy of Sciences

Yanett Contreras

Universiteit Leiden

Kaho Morii

University of Tokyo

National Institutes of Natural Sciences

Kee-Tae Kim

Korea Astronomy and Space Science Institute

University of Science and Technology (UST)

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 903 2 119

Ämneskategorier

Meteorologi och atmosfärforskning

Astronomi, astrofysik och kosmologi

Miljövetenskap

DOI

10.3847/1538-4357/abb81f

Mer information

Senast uppdaterat

2020-12-04