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 present a study on the spatial distribution of N2D+ and N2H+ in thirteenprotostellar systems. Eight of thirteen objects observed with the IRAM 30mtelescope show relative offsets between the peak N2D+ (J=2-1) and N2H+ (J=1-0)emission. We highlight the case of L1157 using interferometric observationsfrom the Submillimeter Array and Plateau de Bure Interferometer of the N2D+(J=3-2) and N2H+ (J=1-0) transitions respectively. Depletion of N2D+ in L1157is clearly observed inside a radius of ~2000 AU (7") and the N2H+ emission isresolved into two peaks at radii of ~1000 AU (3.5"), inside the depletionregion of N2D+. Chemical models predict a depletion zone in N2H+ and N2D+ dueto destruction of H2D+ at T ~ 20 K and the evaporation of CO off dust grains atthe same temperature. However, the abundance offsets of 1000 AU between the twospecies are not reproduced by chemical models, including a model that followsthe infall of the protostellar envelope. The average abundance ratios of N2D+to N2H+ have been shown to decrease as protostars evolve by Emprechtinger etal., but this is the first time depletion zones of N2D+ have been spatiallyresolved. We suggest that the difference in depletion zone radii for N2H+ andN2D+ is caused by either the CO evaporation temperature being above 20 K or anH2 ortho-to-para ratio gradient in the inner envelope.

Resolved Depletion Zones and Spatial Differentiation of N2H+ and N2D+