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

During the embedded phase of pre-main sequence stellar evolution, a diskforms from the dense envelope while an accretion-driven outflow carves out acavity within the envelope. Highly excited H2O emission in spatially unresolvedSpitzer/IRS spectra of a low-mass Class 0 object, NGC 1333 IRAS 4B, haspreviously been attributed to the envelope-disk accretion shock but couldinstead be produced in an outflow. As part of the survey of low-mass sources inthe Water in Star Forming Regions with Herschel (WISH-LM) program, we usedHerschel/PACS to obtain a far-IR spectrum and several Nyquist-sampled spectralimages with to determine the origin of excited H2O emission from NGC 1333 IRAS4B. The spectrum has high signal-to-noise in a rich forest of H2O, CO, and OHlines, providing a near-complete census of far-IR molecular emission from aClass 0 protostar. The excitation diagrams for the three molecules all requirefits with two excitation temperatures, indicating the presence of two physicalcomponents. The highly excited component of H2O emission is characterized bysubthermal excitation of 1500 K gas with a density of 10^5 - 10^7 cm-3,conditions that also reproduce the mid-IR H2O emission detected by Spitzer. Onthe other hand, a high density, low temperature gas can reproduce the H2Ospectrum observed by Spitzer but underpredicts the H2O lines seen by Herschel.Nyquist-sampled spectral maps of several lines show two spatial components ofH2O emission, one centered at 1200 AU south of the central source at theposition of the blueshifted outflow lobe and a second centered on-source. Bothspatial components of the far-IR H2O emission are consistent with emission fromthe outflow. The gas cooling from the IRAS 4B envelope cavity walls isdominated by far-IR H2O emission, in contrast to stronger [O I] and CO coolingfrom more evolved protostars. [one sentence truncated]

Water in star-forming regions with Herschel: highly excited molecular emission from the NGC 1333 IRAS 4B outflow