Cyganowski, CJ, Ilee, JD orcid.org/0000-0003-1008-1142, Brogan, CL et al. (4 more authors) (2022) Discovery of a 500 au Protobinary in the Massive Prestellar Core G11.92–0.61 MM2. The Astrophysical Journal Letters, 931 (2). L31. L31-L31. ISSN 2041-8205
Abstract
We present high-resolution (≲160 au) Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm observations of the high-mass prestellar core candidate G11.92−0.61 MM2, which reveal that this source is in fact a protobinary system with a projected separation of 505 au. The binary components, MM2E and MM2W, are compact (radii <140 au) sources within the partially optically thick dust emission with α0.9 cm−1.3 mm = 2.47–2.94. The 1.3 mm brightness temperatures, Tb = 68.4/64.6 K for MM2E/MM2W, imply internal heating and minimum luminosities L* > 24.7 L⊙ for MM2E and L* > 12.6 L⊙ for MM2W. The compact sources are connected by a "bridge" of lower-surface-brightness dust emission and lie within more extended emission that may correspond to a circumbinary disk. The circumprotostellar gas mass, estimated from ∼0farcs2 resolution VLA 0.9 cm observations assuming optically thin emission, is 6.8 ± 0.9 M⊙. No line emission is detected toward MM2E and MM2W in our high-resolution 1.3 mm ALMA observations. The only line detected is 13CO J = 2–1, in absorption against the 1.3 mm continuum, which likely traces a layer of cooler molecular material surrounding the protostars. We also report the discovery of a highly asymmetric bipolar molecular outflow that appears to be driven by MM2E and/or MM2W in new deep, ∼0farcs5 resolution (1685 au) ALMA 0.82 mm observations. This outflow, traced by low-excitation CH3OH emission, indicates ongoing accretion onto the protobinary system. Overall, the super-Alfvénic models of Mignon-Risse et al. agree well with the observed properties of the MM2E/MM2W protobinary, suggesting that this system may be forming in an environment with a weak magnetic field.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022. The Author(s). This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) |
Keywords: | Star formation; Star forming regions; Protostars; Stellar accretion; Binary stars; Stellar accretion disks |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Astrophysics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 28 Jun 2022 11:28 |
Last Modified: | 28 Jun 2022 11:28 |
Status: | Published |
Publisher: | American Astronomical Society |
Identification Number: | 10.3847/2041-8213/ac69ca |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:188155 |