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Large molecules in the envelope surrounding IRC+10216 总被引：1，自引：0，他引：1
T. J. Millar E. Herbst R. P. A. Bettens 《Monthly notices of the Royal Astronomical Society》2000,316(1):195-203
A new chemical model of the circumstellar envelope surrounding the carbon-rich star IRC+10216 is developed that includes carbon-containing molecules with up to 23 carbon atoms. The model consists of 3851 reactions involving 407 gas-phase species. Sizeable abundances of a variety of large molecules including carbon clusters, unsaturated hydrocarbons and cyanopolyynes have been calculated. Negative molecular ions of chemical formulae and C n H n H radicals are looked at carefully and compared with interferometric observations. 相似文献
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René D. Oudmaijer 《Astrophysics and Space Science》1995,224(1-2):325-328
IRC +10420 is to date the only object that has been proposed to be in the transition from the Red Supergiant Phase to the Wolf-Rayet phase. In this contribution we report on new high resolution optical spectra of IRC +10420. 相似文献
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T.J. Millar J.R. Flores A.J. Markwick 《Monthly notices of the Royal Astronomical Society》2001,327(4):1173-1177
We have updated the chemical model of IRC+10216 developed by Millar, Herbst & Bettens to include recent routes to the formation of sulphuretted hydrocarbons. The routes are based on a quantum chemical study of the S+C2 H system. In addition, we have altered the parent species for sulphur to reflect new observational results. We find that the model calculations give excellent agreement with the observed column densities, and discuss the significance of these reactions to the formation of species as yet unobserved and to dark interstellar clouds. 相似文献
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C. J. Skinner M. Meixner & M. Bobrowsky 《Monthly notices of the Royal Astronomical Society》1998,300(4):L29-L33
Our current understanding of the evolution of solar-type stars suggests that after a period as a red giant star, during which mass loss occurs continuously in the form of a stellar wind, a period of intense mass loss known as a superwind occurs, during which a significant fraction of the envelope of the star is ejected into space, forming the material from which a planetary nebula (PN) will be constructed. It has been suggested that this superwind ejects material from the star in a toroidal or disc-like fashion, rather than isotropically. Here we present Hubble Space Telescope optical images of a toroidal superwind caught in the act: our images of the carbon star IRC+10216, which is believed to be in the final stages of red giant evolution, show that most of its optical emission is a bipolar reflection nebula. We show that the full spectral energy distribution and these images can be modelled as an equatorially enhanced dusty superwind, providing the first direct observational support for the toroidal superwind model, and supporting the 'interacting winds' model of PN formation. 相似文献
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J. M. Winters A. J. Fleischer E. Sedlmayr A. Gauger 《Astrophysics and Space Science》1995,224(1-2):329-332
Synthetic brightness profiles resulting from consistent dynamical models for circumstellar dust shells around long-period variables are presented and discussed with respect to a corresponding observation of IRC +10216. 相似文献
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S. Petrie T. J. Millar A. J. Markwick 《Monthly notices of the Royal Astronomical Society》2003,341(2):609-616
We employ quantum chemical calculations using the CBS-RAD ('Complete Basis Set – Radicals') technique on the C2 N2 H potential energy surface to show that the reaction of HNC with CN is a viable and plausible route to NCCN in cold astrophysical environments. We use detailed chemical kinetic models to predict the abundance of NCCN in TMC-1 and IRC+10216. Radio-astronomical detection of NCCN is precluded by its lack of a dipole moment. We discuss other prospects for its observation in interstellar and circumstellar environments, by space-borne infrared spectroscopy, indirectly by detection of the NCCNH+ ion, or inferentially by detection of its higher-energy, polar isomer CNCN. 相似文献