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Feedback from OB stars on their parent cloud: gas exhaustion rather than gas ejection

Watkins, E. J. and Peretto, N. and Marsh, K. and Fuller, G. A. (2019) Feedback from OB stars on their parent cloud: gas exhaustion rather than gas ejection. Astronomy and Astrophysics, 628 . Art. No. A21. ISSN 0004-6361. doi:10.1051/0004-6361/201935277.

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Context. Stellar feedback from high-mass stars shapes the interstellar medium, and thereby impacts gas that will form future generations of stars. However, due to our inability to track the time evolution of individual molecular clouds, quantifying the exact role of stellar feedback on their star formation history is an observationally challenging task. Aims. In the present study, we take advantage of the unique properties of the G316.75-00.00 massive-star forming ridge to determine how stellar feedback from O-stars impacts the dynamical stability of massive filaments. The G316.75 ridge is 13.6 pc long and contains 18 900 M⊙ of H_2 gas, half of which is infrared dark and half of which infrared bright. The infrared bright part has already formed four O-type stars over the past 2 Myr, while the infrared dark part is still quiescent. Therefore, by assuming the star forming properties of the infrared dark part represent the earlier evolutionary stage of the infrared bright part, we can quantify how feedback impacts these properties by contrasting the two. Methods. We used publicly available Herschel/HiGAL and molecular line data to measure the ratio of kinetic to gravitational energy per-unit-length, α_(vir)^(line), across the entire ridge. By using both dense (i.e. N_2H^+ and NH_3) and more diffuse (i.e. ^(13)CO) gas tracers, we were able to compute α_(vir)^(line) for a range of gas volume densities (~1 × 10^2–1 × 10^5 cm^(−3)). Results. This study shows that despite the presence of four embedded O-stars, the ridge remains gravitationally bound (i.e. α_(vir)^(line) ≤ 2) nearly everywhere, except for some small gas pockets near the high-mass stars. In fact, α_(vir)^(line) is almost indistinguishable for both parts of the ridge. These results are at odds with most hydrodynamical simulations in which O-star-forming clouds are completely dispersed by stellar feedback within a few cloud free-fall times. However, from simple theoretical calculations, we show that such feedback inefficiency is expected in the case of high-gas-density filamentary clouds. Conclusions. We conclude that the discrepancy between numerical simulations and the observations presented here originates from different cloud morphologies and average densities at the time when the first O-stars form. In the case of G316.75, we speculate that the ridge could arise from the aftermath of a cloud-cloud collision, and that such filamentary configuration promotes the inefficiency of stellar feedback. This does very little to the dense gas already present, but potentially prevents further gas accretion onto the ridge. These results have important implications regarding, for instance, how stellar feedback is implemented in cosmological and galaxy scale simulations.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Watkins, E. J.0000-0002-7365-5791
Peretto, N.0000-0002-6893-602X
Fuller, G. A.0000-0001-8509-1818
Additional Information:© 2019 ESO. Article published by EDP Sciences. Received 14 February 2019; Accepted 13 June 2019; Published online 30 July 2019. E.J.W. is supported by the Science and Technology Facilities Council (STFC). N.P. wishes to acknowledge support from STFC under grant number ST/N000706/1. This research has made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018). This research has also made use of the python packages astrodendro, colorcet, matplotlib, multicolorfits, numpy, scipy and skimage. This research also makes use of the software GILDAS and STARLINK.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)ST/N000706/1
Subject Keywords:stars: formation – stars: massive – infrared: ISM – methods: observational – ISM: kinematics and dynamics – HII regions
Record Number:CaltechAUTHORS:20190815-160705283
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Official Citation:Feedback from OB stars on their parent cloud: gas exhaustion rather than gas ejection. E. J. Watkins, N. Peretto, K. Marsh and G. A. Fuller. A&A, 628 (2019) A21. DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97932
Deposited By: Tony Diaz
Deposited On:15 Aug 2019 23:35
Last Modified:16 Nov 2021 17:35

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