In addition, roughly two dozen molecules have been detected exclusively in circumstellar gas - specifically around the source IRC+10216. These molecules include species containing the elements Na, Mg, K, and Al, in addition to the elements represented by molecules formed in the interstellar medium.

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Derived from thermochemical data recommended in NIST Standard Reference Database Number 69 (a.k.a. the NIST Chemistry Web book), ed. P. J. Linstrom, & W. G. Mallard, March 2003, National Institute of Standards and Technology, Gaithersburg MD 20899; available on-line at http://webbook.nist.gov

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... APEX

The Atacama Pathfinder Experiment (APEX) is a collaboration of the Max-Planck-Institut für Radioastronomie, the European Southern Observatory, and the Onsala Space Observtory.

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... primarily

Reaction with H₂ to form HCF⁺, considered by Morino et al. (2000) to dominate the destruction of interstellar CF⁺, is in fact substantially endothermic² (by $\sim$ 2 eV) and therefore of negligible importance (NWS).

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... fluorine

The elemental abundance of fluorine is of particular interest because the nucleosynthetic origin of fluorine remains controversial. Fluorine is produced in stars on the asymptotic giant branch (Jorissen et al. 1992; Werner et al. 2005), but there is no consensus on the relative contributions of other sources such as Wolf-Rayet stars and type II supernovae (e.g. Renda et al. 2004; Palacios et al. 2005). Because AGB stars exhibit a large enhancement in the fluorine abundance (up to a factor $\sim$ 250), it will be interesting to search for CF⁺ in circumstellar envelopes as well as in the wind-blown bubbles surrounding Wolf-Rayet stars (Marston et al. 1999; Marston 2001; Rizzo et al. 2003).

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