Crescent-shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA
Abstract We report on an Atacama Large Millimeter/submillimeter Array study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The 12 CO( J = 2–1) images have an angular resolution of ∼1″ (∼250 au) and show high-velocity blueshifted (≳70 km s −1 ) and redshifted (≳5...
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Published in | The Astrophysical journal Vol. 945; no. 1; pp. 63 - 71 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Philadelphia
The American Astronomical Society
01.03.2023
IOP Publishing |
Subjects | |
Online Access | Get full text |
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Summary: | Abstract
We report on an Atacama Large Millimeter/submillimeter Array study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The
12
CO(
J
= 2–1) images have an angular resolution of ∼1″ (∼250 au) and show high-velocity blueshifted (≳70 km s
−1
) and redshifted (≳50 km s
−1
) emissions, which have 3000 au scale crescent-shaped structures around the protostellar disk traced in the 1.3 mm continuum. Because the high-velocity components of the CO emission are associated with the protostar, we concluded that the emission traces the pole-on outflow. The blueshifted outflow lobe has a clear layered velocity gradient with a higher-velocity component located on the inner side of the crescent shape, which can be explained by a model of an outflow with a higher velocity in the inner radii. Based on the directly driven outflow scenario, we estimated the driving radii from the observed outflow velocities and found that the driving region extends over 2 orders of magnitude. The
13
CO emission traces a complex envelope structure with arc-like substructures with lengths of ∼1000 au. We identified the arc-like structures as streamers because they appear to be connected to a rotating infalling envelope. DK Cha is useful for understanding characteristics that are visible by looking at nearly face-on configurations of young protostellar systems, providing an alternative perspective for studying the star formation process. |
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Bibliography: | AAS43633 Interstellar Matter and the Local Universe |
ISSN: | 0004-637X 1538-4357 |
DOI: | 10.3847/1538-4357/acb930 |