# Investigating the complex velocity structures within dense molecular cloud cores with GBT-Argus

## Author(s): Chen, Che-Yu; Storm, Shaye; Li, Zhi-Yun; Mundy, Lee G; Frayer, David; et al

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 Abstract: We present the first results of high-spectral resolution (0.023 km s(-1)) N2H+ observations of dense gas dynamics at core scales (similar to 0.01 pc) using the recently commissioned Argus instrument on the Green Bank Telescope (GBT). While the fitted linear velocity gradients across the cores measured in our targets nicely agree with the well-known power-law correlation between the specific angular momentum and core size, it is unclear if the observed gradients represent core-scale rotation. In addition, our Argus data reveal detailed and intriguing gas structures in position-velocity (PV) space for all five targets studied in this project, which could suggest that the velocity gradients previously observed in many dense cores actually originate from large-scale turbulence or convergent flow compression instead of rigid-body rotation. We also note that there are targets in this study with their star-forming discs nearly perpendicular to the local velocity gradients, which, assuming the velocity gradient represents the direction of rotation, is opposite to what is described by the classical theory of star formation. This provides important insight on the transport of angular momentum within star-forming cores, which is a critical topic on studying protostellar disc formation. Publication Date: Nov-2019 Electronic Publication Date: 19-Sep-2019 Citation: Chen, Che-Yu, Storm, Shaye, Li, Zhi-Yun, Mundy, Lee G, Frayer, David, Li, Jialu, Church, Sarah, Friesen, Rachel, Harris, Andrew, Looney, Leslie W, Offner, Stella, Ostriker, Eve C, Pineda, Jaime E, Tobin, John, Chen, Hope H-H. (2019). Investigating the complex velocity structures within dense molecular cloud cores with GBT-Argus. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 490 (527 - 539. doi:10.1093/mnras/stz2633 DOI: doi:10.1093/mnras/stz2633 ISSN: 0035-8711 EISSN: 1365-2966 Related Item: https://ui.adsabs.harvard.edu/abs/2019MNRAS.490..527C/abstract Pages: 527 - 539 Type of Material: Journal Article Journal/Proceeding Title: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Version: Final published version. Article is made available in OAR by the publisher's permission or policy.