University of Hertfordshire

From the same journal

From the same journal

Before the first supernova: combined effects of H II regions and winds on molecular clouds

Research output: Contribution to journalArticlepeer-review


  • J. Ngoumou
  • B. Ercolano
  • I.~A. Bonnell
  • James Dale
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Original languageEnglish
Pages (from-to)694-712
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Early online date9 Jun 2014
Publication statusPublished - 21 Jul 2014


We model the combined effects of photoionization and momentum-driven winds from O-stars on molecular clouds spanning a parameter space of initial conditions. The dynamical effects of the winds are very modest. However, in the lower mass clouds, they influence the morphologies of the H II regions by creating 10-pc-scale central cavities. The inhomogeneous structures of the model giant molecular clouds (GMCs) make them highly permeable to photons, ionized gas and supernova ejecta, and the leaking of ionized gas in particular strongly affects their evolution, reducing the effectiveness of feedback. Nevertheless, feedback is able to expel large fractions of the mass of the lower escape velocity clouds. Its impact on star formation is more modest, decreasing final star formation efficiencies by 10–20 per cent, and the rate of change of the star formation efficiency per freefall time by about one third. However, the clouds still form stars substantially faster than observed GMCs.


This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

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