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Squeezed between shells? The origin of the Lupus I molecular cloud: II. APEX CO and GASS HI observations


Gaczkowski, B and Roccatagliata, V and Flaischlen, S and Kroll, D and Krause, MGH and Burkert, A and Diehl, R and Fierlinger, K and Ngoumou, J and Preibisch, T, Squeezed between shells? The origin of the Lupus I molecular cloud: II. APEX CO and GASS HI observations, Astronomy and Astrophysics, 608 Article A102. ISSN 0004-6361 (2017) [Refereed Article]


Copyright Statement

Copyright 2017 ESO. Reproduced with permission from Astronomy & Astrophysics

DOI: doi:10.1051/0004-6361/201628508


Context. Lupus I cloud is found between the Upper Scorpius (USco) and Upper Centaurus-Lupus (UCL) subgroups of the Scorpius-Centaurus OB association, where the expanding USco H I shell appears to interact with a bubble currently driven by the winds of the remaining B stars of UCL.

Aims. We investigate whether the Lupus I molecular could have formed in a colliding flow, and in particular, how the kinematics of the cloud might have been influenced by the larger scale gas dynamics.

Methods. We performed APEX 13CO(21)and C18O(21) line observations of three distinct parts of Lupus I that provide kinematic information on the cloud at high angular and spectral resolution. We compare those results to the atomic hydrogen data from the GASS H i survey and our dust emission results presented in the previous paper. Based on the velocity information, we present a geometric model for the interaction zone between the USco shell and the UCL wind bubble.

Results. We present evidence that the molecular gas of Lupus Iis tightly linked to the atomic material of the USco shell. The CO emission in Lupus Iis found mainly at velocities between vLSR = 36 km s-1, which is in the same range as the H i velocities. Thus, the molecular cloud is co-moving with the expanding USco atomic H i shell. The gas in the cloud shows a complex kinematic structure with several line-of-sight components that overlay each other. The nonthermal velocity dispersion is in the transonic regime in all parts of the cloud and could be injected by external compression. Our observations and the derived geometric model agree with a scenario in which Lupus Iis located in the interaction zone between the USco shell and the UCL wind bubble.

Conclusions. The kinematics observations are consistent with a scenario in which the Lupus Icloud formed via shell instabilities. The particular location of Lupus I between USco and UCL suggests that counterpressure from the UCL wind bubble and pre-existing density enhancements, perhaps left over from the gas stream that formed the stellar subgroups, may have played a role in its formation.

Item Details

Item Type:Refereed Article
Keywords:ISM: bubbles, ISM: clouds, ISM: kinematics and dynamics, ISM: structure, ISM: molecules, radio lines: ISM
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Galactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Krause, MGH (Dr Martin Krause)
ID Code:123486
Year Published:2017
Web of Science® Times Cited:5
Deposited By:Mathematics and Physics
Deposited On:2018-01-10
Last Modified:2018-04-27
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