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 high-spectral resolution observations from 12.96 - 13.33 micronstowards Orion IRc2 using the mid-infrared spectrograph, EXES, on SOFIA. Theseobservations probe the physical and chemical conditions of the Orion hot core,which is sampled by a bright, compact, mid-infrared background continuum sourcein the region, IRc2. All ten of the rovibrational C2H2 transitions expected inour spectral coverage, are detected with high S/N, yielding continuous coverageof the R-branch lines from J=9-8 to J=18-17, including both ortho and paraspecies. Eight of these rovibrational transitions are newly reporteddetections. The isotopologue, 13CCH2, is clearly detected with highsignal-to-noise. This enabled a direct measurement of the 12C/13C isotopicratio for the Orion hot core of 14 +/- 1 and an estimated maximum value of 21.We also detected several HCN rovibrational lines. The ortho and para C2H2ladders are clearly separate and tracing two different temperatures, 226 K and164 K, respectively, with a non-equilibrium ortho to para ratio (OPR) of 1.7+\- 0.1. Additionally, the ortho and para V_LSR values differ by about 1.8 +/-0.2 km/s, while, the mean line widths differ by 0.7 +/- 0.2 km/s, suggestingthat these species are not uniformly mixed along the line of sight to IRc2. Wepropose that the abnormally low C2H2 OPR could be a remnant from an earlier,colder phase, before the density enhancement (now the hot core) was impacted byshocks generated from an explosive event 500 yrs ago.

High Spectral Resolution SOFIA/EXES Observations of C2H2 towards Orion-IRc2