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

Proplyds and stars inside HII-regions are a well studied phenomenon. It ispossible that they were triggered by the expansion of the HII-region itself.Here, we present calculations on the dynamics of HII-regions. We show that thetriggered stars that form in the expanding shell of swept up material aroundthe HII region rarely return into the HII regions on timescales that areinferred for the proplyds and observed young stars. However, in very denseenvironments like Orion, the triggered stars return in time. Thus, our modelcan explain why proplyds are barely observed in other HII regions. We proposethat the properties of young stellar objects in HII regions in general dependcritically on the distance from the massive, ionizing central star cluster.Closest in, there are proplyds, where the disk of a young star interactsdirectly with the feedback of the massive star. Further out are Class IIprotostars, where the ionization already removed the envelope. Even furtheraway, one should find Class I stars, which either have been triggered by theionizing radiation or pre-existed and have not lost their envelope yet. Thisradial sequence is not necessarily an age sequence but rather a result of thedwindling importance of stellar winds and ionizing radiation with distance. Weinvestigate the observational signature of triggered star formation and findthat the stellar distribution for ionization triggered star formation shows adistinct feature, a peak at the current position of the ionization front.Therefore, it is generally possible to tell triggered and in situ distributionsof stars apart.

The Return of the Proplyds - Understanding the Dynamics of Ionization Triggered Stars