| Name | OT2_ewirst01_2 |
| Title | Determining the Ice Desorption Mechanism in Cold Molecular Clouds |
| URL | http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342249424&instrument_name=HIFI&product_level=LEVEL0&compress=true |
| DOI | https://doi.org/10.5270/esa-7psepc7 |
| Author | European Space Agency |
| Description | Interstellar ices are readily formed from accretion of atoms and molecules onto cold dust grains, and in dense cores the gas would be depleted in all heavy molecules were it not for the operation of some non-thermal desorption process. Methanol molecules are only formed efficiently from hydrogenation of CO molecules accreted onto grains, but is still widely observed in cold dense clouds. This attests to the operation of desorption processes not related to the heating up of the gas from a nearby star. Proposed mechanisms for injecting the ice mantle molecules into the gas-phase includes both continuous processes, such as cosmic-ray impacts, photodesorption, or ejection upon formation, and more transient ones such as clump-clump collisions, and effects of embedded protostars influencing the chemistry through shocks or dissipation of magnetohydrodynamic (MHD) waves. The presence of distinct peaks of methanol emission at positions significantly offset from protostars, however, implies that the desorption process is indeed transient, and likely to also disrupt a major part of the ice mantles. This would lead to very high water abundances at these peaks, clearly distinguishable from what is expected from photodesorption or steady-state gas-phase chemistry. In order to constrain the active ice desorption mechanisms in cold molecular clouds, we thus propose to use HIFI to observe the ground state transition of ortho water at three different methanol peaks: two at different distances from the Class I protostar Barnard 5 IRS1, and one in L1512, a region free from protostellar activity. |
| Publication | Cold Water Vapor in the Barnard 5 Molecular Cloud . Wirström E. S. et al. . The Astrophysical Journal Letters, Volume 788, Issue 2, article id. L32, 5 pp. (2014). . 788 . 10.1088\/2041-8205\/788\/2\/L32 . 2014ApJ...788L..32W , |
| Instrument | HIFI_HifiPoint_pos |
| Temporal Coverage | 2012-08-11T06:48:41Z/2012-08-29T19:45:10Z |
| Version | SPG v14.1.0 |
| Mission Description | 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. |
| Creator Contact | https://support.cosmos.esa.int/h®erschel/ |
| Date Published | 2013-02-28T19:41:50Z |
| Publisher And Registrant | European Space Agency |
| Credit Guidelines | European Space Agency, 2013, Determining The Ice Desorption Mechanism In Cold Molecular Clouds, SPG v14.1.0, European Space Agency, https://doi.org/10.5270/esa-7psepc7 |