The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). VI. The Core-scale CO Depletion
Artikel i vetenskaplig tidskrift, 2022

Studying the physical and chemical properties of cold and dense molecular clouds is crucial for the understanding of how stars form. Under the typical conditions of infrared dark clouds, CO is removed from the gas phase and trapped onto the surface of dust grains by the so-called depletion process. This suggests that the CO-depletion factor (f D ) can be a useful chemical indicator for identifying cold and dense regions (i.e., prestellar cores). We have used the 1.3 mm continuum and C18O (2-1) data observed at the resolution of ∼5000 au in the ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES) to construct averaged maps of f D in 12 clumps to characterize the earliest stages of the high-mass star formation process. The average f D determined for 277 of the 294 ASHES cores follows an unexpected increase from the prestellar to the protostellar stage. If we exclude the temperature effect due to the slight variations in the NH3 kinetic temperature among different cores, we explain this result as a dependence primarily on the average gas density, which increases in cores where protostellar conditions prevail. This shows that f D determined in high-mass star-forming regions at the core scale is insufficient to distinguish among prestellar and protostellar conditions for the individual cores and should be complemented by information provided by additional tracers. However, we confirm that the clump-averaged f D values correlate with the luminosity-to-mass ratio of each source, which is known to trace the evolution of the star formation process.

Författare

Giovanni Sabatini

Istituto di Radioastronomia

Stefano Bovino

Istituto di Radioastronomia

Universidad de Concepción

Patricio Sanhueza

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

Kaho Morii

University of Tokyo

National Astronomical Observatory of Japan

Shanghuo Li

Korea Astronomy and Space Science Institute

Elena Redaelli

Max-Planck-Gesellschaft

Q. Zhang

Harvard-Smithsonian Center for Astrophysics

X. Lu

Shanghai Astronomical Observatory

S. Feng

Xiamen University

Daniel Tafoya

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

Natsuko Izumi

Academia Sinica

T. Sakai

University of Electro-Communications

Ken’ichi Tatematsu

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

David Allingham

University of Newcastle

Astrophysical Journal

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

Vol. 936 1 80

Ämneskategorier

Astronomi, astrofysik och kosmologi

Multidisciplinär geovetenskap

DOI

10.3847/1538-4357/ac83aa

Mer information

Senast uppdaterat

2022-09-26