===== On Phosphine, PH3 in Circumstellar Envelopes of Late-Type Stars =====

The detection of a circumstellar feature was tentatively attributed to the //J// = 1 – 0 transition of PH<sub>3</sub> by two groups almost simultaneously:\\
E. D. Tenenbaum and L. M. Ziurys,\\
**[[https://doi.org/10.1086/589973|A Search for Phosphine in Circumstellar Envelopes: PH<sub>3</sub> in IRC +10216 and CRL 2688 ?]]**\\
//Astrophys. J.// **680**, L121–L124 (2008).\\
M. Agúndez, J. Cernicharo, J. R. Pardo, M. Guélin, T. G. Phillips,\\
**[[https://doi.org/10.1051/0004-6361:200810193|Tentative Detection of Phosphine in IRC +10216]]**\\
//Astron. Astrophys.// **485**, L33–L36 (2008).\\
The first work ascribed a feature at //v//<sub>LSR</sub> of the star to PH<sub>3</sub> close to the star. The second paper, however, convincingly assigned that feature to SiS in its //v// = 4 excited vibrational state. In the first work, the feature was not only detected in the envelope of the carbon-rich AGB star IRC +10216, but also in the protoplanetary nebula CRL 2688. The feature was also searched for in the protoplanetary nebula CRL 618, but was found to be overlapped by a line of HC<sub>3</sub>N in its //v//<sub>7</sub> = 4 excited vibrational state.

M. Agúndez, J. Cernicharo, L. Decin, P. Encrenaz, and D. Teyssier,\\
reported recently on the\\
**[[https://doi.org/10.1088/2041-8205/790/2/L27|Confirmation of Circumstellar Phosphine]]**\\
//Astrophys. J.// **790**, Art. No. L27 (2014).\\
The essentially overlapping //J// = 2 – 1, //K// = 0 and 1 transitions were observed in emission near 533.8 GHz with the //Herschel///HIFI instrument toward the famous carbon-rich AGB star CW Leonis, also known as IRC +10216.


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Contributor(s): H. S. P. Müller; 06, 2008; 07, 2014

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