Context. The star-formation rates and stellar densities found in young
massive clusters suggest that these stellar systems originate from gas
at densities of n(H2) > 106 cm-3.
Until today, however, the physical characterization of this ultra high
density material remains largely unconstrained in observations.
Aims: We investigate the density properties of the star-forming gas in
the OMC-1 region located in the vicinity of the Orion Nebula Cluster
(ONC). Methods: We mapped the molecular emission at 652 GHz in
OMC-1 as part of the APEX-SEPIA660 Early Science. Results: We
detect bright and extended N2H+ (J = 7-6) line
emission along the entire OMC-1 region. Comparisons with previous ALMA
data of the (J = 1-0) transition and radiative transfer models indicate
that the line intensities observed in this N2H+
(7-6) line are produced by large mass reservoirs of gas at densities
n(H2) > 107 cm-3.
Conclusions: The first detection of this N2H+
(7-6) line at parsec-scales demonstrates the extreme density conditions
of the star-forming gas in young massive clusters such as the ONC. Our
results highlight the unique combination of sensitivity and mapping
capabilities of the new SEPIA660 receiver for the study of the ISM
properties at high frequencies.
The reduced datacubes are only available at the CDS via anonymous ftp to
(ftp://22.214.171.124) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/644/A133
This publication is based on data acquired with the Atacama Pathfinder
Experiment (APEX). APEX is a collaboration between the
Max-Planck-Institut fur Radioastronomie, the European Southern
Observatory, and the Onsala Space Observatory.
- ISM: clouds
- ISM: molecules
- ISM: structure
- submillimeter: ISM
- DARK CLOUDS