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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present high resolution (0.''12 x 0.''079) observations of theultracompact HII region G10.6-0.4 in 23 GHz radio continuum and the NH3(3,3)line. Our data show that the infall in the molecular material is largelyspherical, and does not flatten into a molecular disk at radii as small as 0.03pc. The spherical infall in the molecular gas matches in location and velocitythe infall seen in the ionized gas. We use a non-detection to place a stringentupper limit on the mass of an expanding molecular shell associated withpressure driven expansion of the HII region. These data support a scenario inwhich the molecular accretion flow passes through an ionization front andbecomes an ionized accretion flow onto one or more main sequence stars, not theclassical pressure-driven expansion scenario. In the continuum emission we seeevidence for externally ionized clumps of molecular gas, and cavities evacuatedby an outflow from the central source.Comment: Accepted for publication in Astrophysical Journal Letter

Spherical Infall in G10.6-0.4: Accretion through an Ultracompact H ii Region