Williams, Peter G. and White, Glenn J.
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The study reports observations of the circumstellar envelope IRC+10216 obtained with the 15-m James Clerk Maxwell Telescope. Maps with the 15" FWHM beam were made in the CO J = 3-2, CS J = 7-6, and HCN J = 4-3 transitions. The HCN J = 4-3 intensity is significantly greater than that of CO J = 3-2, but drops off almost twice as rapidly with distance from the source center. This rapid fall-off of the HCN intensity is indicative of the dominance of radiative excitation, which contrasts with the mainly collisional mechanism driving CO excitation. Single spectra at or near the source center are also presented for the isotopes 13CO, H13CN, C34S, for the J = 3-2 line of HCN and its isotope H13CN and for CO J = 4-3. Simple modeling results in estimates of relative abundances and excitation temperatures of CO, HCN, and CS, and an upper limit to the neutral carbon abundance.
|Item Type:||Journal Article|
|Copyright Holders:||1992 European Southern Observatory|
|Keywords:||molecular spectra; stellar envelopes; astronomical models; astronomical spectroscopy; carbon monoxide; hydrocyanic acid; submillimeter waves|
|Academic Unit/Department:||Science > Physical Sciences
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)|
|Depositing User:||G. J. White|
|Date Deposited:||30 May 2012 14:40|
|Last Modified:||18 Jan 2016 18:20|
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