Banerjee, D.P.K.; Barber, R.J.; Ashok, N.M.; Tennyson, J.; (2005) Near-Infrared water lines in V838 Monocerotis. The Astrophysical Journal Letters , 627 (2) L141-L144. 10.1086/432442.

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Abstract

Employing spectra obtained with the new Keck I HIRES near-UVsensitive detector, we have performed a comprehensive chemical composition analysis of the binary blue metal-poor star CS 29497-030. Abundances for 29 elements and upper limits for an additional seven have been derived, concentrating on elements largely produced by means of neutron-capture nucleosynthesis. Included in our analysis are the two elements that define the termination point of the slow neutron-capture process, lead and bismuth. We determine an extremely high value of [Pb/Fe] = +3.65 ± 0.07 ( = 0.13) from three features, supporting the single-feature result obtained in previous studies. We detect Bi for the first time in a metal-poor star. Our derived Bi/Pb ratio is in accord with those predicted from the most recent FRANEC calculations of the slow neutron-capture process in low-mass asymptotic giant branch (AGB) stars. We find that the neutron-capture elemental abundances of CS 29497-030 are best explained by an AGB model that also includes very significant amounts of pre-enrichment of rapid neutron-capture process material in the protostellar cloud out of which the CS 29497-030 binary system formed. Mass transfer is consistent with the observed [Nb/Zr] 0. Thus, CS 29497-030 is both an r+s and "extrinsic AGB" star. Furthermore, we find that the mass of the AGB model can be further constrained by the abundance of the light odd-element Na.

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