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arXiv · 2606.00631

Ca-bearing cyanopolyynes in IRC+10216

T. J. Millar
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Abstract

In recent years, a number of metal-containing, carbon-chain species have been detected in the external circumstellar envelope of the carbon-rich AGB star IRC+10216. The most common metal detected in such species is Mg, for which molecules as large as MgC$_5$N, MgC$_5$N$^+$, MgC$_6$H and MgC$_6$H$^+$ have been observed. In this paper, we calculate the likely abundances of the Ca-bearing cyanopolyynes, CaC$_{2n+1}$N for n = 1-4, drawing the conclusion that the observed abundance of CaNC must be made from much larger Ca-terminated cyanopolyyne ions, which requires considerable rearrangement in their dissociative recombination. We pay particular attention to the detectability of CaC$_3$N whose rotational spectrum has recently been measured.

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T. J. Millar. 2026-05-30. Ca-bearing cyanopolyynes in IRC+10216. https://doi.org/10.1093/mnras%2Fstag1002

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