English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We explore to what extent simple algebraic models can be used to describe HII regions when winds, radiation pressure, gravity and photon breakout areincluded. We a) develop algebraic models to describe the expansion ofphotoionised H II regions under the influence of gravity and accretion inpower-law density fields with $\rho \propto r^{-w}$, b) determine when termsdescribing winds, radiation pressure, gravity and photon breakout becomesignificant enough to affect the dynamics of the H II region where $w=2$, andc) solve these expressions for a set of physically-motivated conditions. Wefind that photoionisation feedback from massive stars is the principal mode offeedback on molecular cloud scales, driving accelerating outflows frommolecular clouds in cases where the peaked density structure around youngmassive stars is considered at radii between $\sim$0.1 and 10-100 pc. Under alarge range of conditions the effect of winds and radiation on the dynamics ofH II regions is around 10% of the contribution from photoionisation. The effectof winds and radiation pressure are most important at high densities, eitherclose to the star or in very dense clouds such as those in the CentralMolecular Zone of the Milky Way. Out to $\sim$0.1 pc they are the principaldrivers of the H II region. Lower metallicities make the relative effect ofphotoionisation even stronger as the ionised gas temperature is higher.

When H II Regions are Complicated: Considering Perturbations from Winds, Radiation Pressure, and Other Effects