| Name | OT2_hgupta_2 |
| Title | A Deep Search for the Molecular Anions CN ^- , CCH ^- , OH ^- , and SH ^- in the Galaxy |
| URL | http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342270605&instrument_name=HIFI&product_level=LEVEL0&compress=true |
| DOI | https://doi.org/10.5270/esa-1xkezgu |
| Author | gupta, h. |
| Description | We propose a sensitive search towards six Galactic sources for the small negative molecular ions (anions) --- CN ^- , CCH ^- , OH ^- , and SH ^- --- with {it Herschel.s} Heterodyne Instrument for the Far-Infrared (HIFI). The full significance of anions in astrophysics is far from understood, and molecular anions may have a much broader impact on the chemistry and physics of astronomical sources than is currently appreciated. In dark clouds and low-mass star-forming regions, reactions of molecular anions are thought to enhance the abundances of neutral polyynes and cyanopolyynes. In circumstellar shells of evolved carbon stars, anions are theorized to form by proton transfer reactions of neutral carbon chain radicals with H ^- , as well as through reactions of atomic N with large carbon chain anions. By influencing the ambipolar diffusion rate, anions may regulate the dynamics of star formation in magnetized plasmas around collapsing molecular cloud cores. Because the abundances of anions are sensitive to electron attachment and photodetachment rates, anions can serve as direct probes of electron densities and cosmic-ray ionization and photoionization rates within interstellar clouds, provided the formation and destruction processes of anions are known.The main question we seek to address is just how widespread anions are in the Galaxy. The four anions we propose to study are structurally simple molecules, with precursors that are abundant in the interstellar gas. The observations here will provide key information on the distribution small molecular anions, which, when combined with chemical models of the observed anion abundances and their dependence on conditions within their astrophysical environments, will advance our understanding of the role of anions in the physics and chemistry ofastronomical sources. |
| Publication | |
| Instrument | HIFI_HifiPoint_dbs |
| Temporal Coverage | 2013-04-20T07:43:36Z/2013-04-20T14:15:14Z |
| 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 | 2013-10-20T11:18:57Z |
| Keywords | Herschel, HSC, submillimetre, far-infrared, HIFI, PACS, SPIRE |
| Publisher And Registrant | European Space Agency |
| Credit Guidelines | European Space Agency, gupta et al., 2013, 'A Deep Search for the Molecular Anions CN elev- comma CCH elev- comma OH elev- comma and SH elev- in the Galaxy', SPG v14.1.0, European Space Agency, https://doi.org/10.5270/esa-1xkezgu |