2002AJ....123.1993R

We report on photometry and high-resolution spectroscopy for IRAS 19285+0517. The spectral energy distribution based on visible and near-infrared photometry and far-infrared fluxes shows that the star is surrounded by dust at a temperature of T_d∼250 K. Spectral line analysis shows that the star is a K giant with a projected rotational velocity of vsini=9±2 km.s^–1. We determined the atmospheric parameters: T_eff=4500 K, logg=2.5, ξ_t=1.5 km.s^–1, and [Fe/H]=0.14 dex. The LTE abundance analysis shows that the star is Li-rich [logε(Li)=2.5±0.15], but with essentially normal C, N, O, and metal abundances. Spectral synthesis of molecular CN lines yields the carbon isotopic ratio ¹²C/¹³C=9±3, a signature of post-main-sequence evolution and dredge-up on the red giant branch (RGB). Analysis of the Li resonance line at 6707 Å for different ⁶Li/⁷Li ratios shows that the Li profile can be best fitted with a predicted profile for pure ⁷Li. Far-infrared excess, high Li abundance, and rapid rotation suggest that a planet has been swallowed or, perhaps, that an instability in the RGB outer layers triggered a sudden enrichment of Li and caused mass loss.