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/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Regions of massive star formation offer some of the best and mosteasily-observed examples of radiation hydrodynamics. Boundaries wherefully-ionized H II regions transition to neutral/molecular photodissociationregions (PDRs) are of particular interest because marked temperature anddensity contrasts across the boundaries lead to evaporative flows and fluiddynamical instabilities that can evolve into spectacular pillar-likestructures. When detached from their parent clouds, pillars become ionizedglobules that often harbor one or more young stars. H2 molecules at theinterface between a PDR and an H II region absorb ultraviolet light frommassive stars, and the resulting fluoresced infrared emission lines are anideal way to trace this boundary independent of obscuring dust. This paperpresents H2 images of four regions of massive star formation that illustratedifferent types of PDR boundaries. The Ara OB1 star formation region contains astriking long wall that has several wavy structures which are present in H2,but the emission is not particularly bright because the ambient UV fluxes arerelatively low. In contrast, the Carina star formation region shows strong H2fluorescence both along curved walls and at the edges of spectacular pillarsthat in some cases have become detached from their parent clouds. Theless-spectacular but more well-known Eagle Nebula has two regions that havestrong fluorescence in addition to its pillars. While somewhat older than theother regions, Cyg OB2 has the highest number of massive stars of the regionssurveyed and contains many isolated, fluoresced globules that have head-tailmorphologies which point towards the sources of ionizing radiation. Theseimages provide a collection of potential astrophysical analogs that may relateto ablated interfaces observed in laser experiments of radiation hydrodynamics.

Irradiated Interfaces in the Ara OB1, Carina, Eagle Nebula, and Cyg OB2 Massive Star Formation Regions