|A HIFI study to determine whether or not ammonia truly traces the densest regions of molecular hot cores
|Ammonia is a widely observed astrophysical molecule and a key tracer of dense gas in the interstellar medium. Inversion transitions of ammonia have been used for many years as a temperature and column density diagnostic toward massive star forming regions. Ground based observations furthermore, point to the presence of hot, presumably dense, gas close to embedded protostars. These same data, however, lack the density sensitivity to conclusively constrain the density of the ammonia emitting gas. Thus, whether or not ammonia is truly tracing the hottest, densest gas closest to an embedded protostar is effectively unknown. The rotation transitions of ammonia, which are unavailable from ground based observatories, have the required density sensitivity to resolve whether or not ammonia truly traces the densest regions close to newly formed massive stars. We propose here to use HIFI to observe seven rotation lines of ammonia toward three molecular hot cores each with clear evidence for hot ammonia. These observations provide the only way to know if this emission also probes dense regions close to massive stars. In sum, the proposed observations require only a modest time investment and represent science that only Herschel-HIFI can do.
|Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
|Publisher And Registrant
|European Space Agency
|European Space Agency, 2013, OT2_ncrocket_1, SPG v14.1.0. https://doi.org/10.5270/esa-kkvdhkt