| タイトル | Optical spectroscopy of carbon-rich proto-planetary nebulae |
| 著者（英） | Hrivnak, Bruce J. |
| 著者所属（英） | NASA Marshall Space Flight Center|NASA Goddard Space Flight Center |
| 発行日 | 1995-01-01 |
| 言語 | eng |
| 内容記述 | In this paper, we present a medium-resolution (3 A) spectroscopic study of six proto-planetary nebulae (PPN), post-asymptotic giant branch (AGB) objects with large infrared excesses. All six are found to display the spectra of G supergiants. However, they also show molecular carbon features, C2 and in most cases C3, and strong absorption lines due to s-process elements. Other evidences of a carbon-rich nature are found in published molecular-line millimeter emissions (CO and HCN) and 3.3 micrometer features attributed to polycyclic aromatic hydrocarbons. These properties are all in accord with what one would expect in a post-AGB star in which carbon-rich materials formed in thermal pulses is dredged up to the surface of a mass-losing object. A correlation is found between the presence of molecular C2 absorption and the presence of the unidentified 21 micrometer emission feature. This strengthens the suggestion that carbon is a major component of the molecule producing this unidentified feature. Four additional proto-planetary nebulae which share some of these properties are also discussed. |
| NASA分類 | ASTRONOMY |
| レポートNO | 95A79856 |
| 権利 | Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/307956 |
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