BD+48 740—Li OVERABUNDANT GIANT STAR WITH A PLANET: A CASE OF RECENT ENGULFMENT?

We report the discovery of a unique object, BD+48 740, a lithium overabundant giant with A (Li) = 2.33 ± 0.04 (where A (Li) = log n Li / n H + 12), that exhibits radial velocity (RV) variations consistent with a 1.6 M J companion in a highly eccentric, e = 0.67 ± 0.17, and extended, a = 1.89 AU ( P = 771 days), orbit. The high eccentricity of the planet is uncommon among planetary systems orbiting evolved stars and so is the high lithium abundance in a giant star. The ingestion by the star of a putative second planet in the system originally in a closer orbit could possibly allow for a single explanation to these two exceptional facts. If the planet candidate is confirmed by future RV observations, it might represent the first example of the remnant of a multiple planetary system recently affected by stellar evolution.