Spectroscopy of open cluster UBC 1052

A strict line-by-line differential analysis was carried out using a reference RC star and a solar analogue in the OC M 67, allowing us to derive very precise abundances for each star (a median precision in [X/H] of ~0.06dex). We also acquired GIRAFFE spectra for other candidate member stars and derived their radial velocities. We determine that UBC 1052 has an age of 2.25+/-0.25Gyr, a distance of 3.11+/-0.07kpc, an extinction of A_V_=1.23mag, and a mean radial velocity of 34.0+/-0.6km/s.

We find that the four RC stars have fully compatible chemical abundances, thus confirming UBC 1052 as a real OC. It has [Fe/H]=+0.05+/-0.01dex, and with [X/H] dispersions among the four stars <0.03dex for 20 elements, we give conservative limits for chemical inhomogeneities at ~0.05dex for these species. UBC 1052 stands out as the oldest and highest-|Z| inner-disc OC studied at high resolution to date, being located in the poorly sampled inner Galactic region where old OCs and OCs with large maximum excursions from the plane are scarce.

Its relatively low [Fe/H] at its Rgc suggests it is a rare candidate for an inward-migrated OC in the inner disc. Its detailed abundance pattern (e.g. [Ba/Zr] and [Nd/Y]) shows some interesting features that appear to be unique in the current census of OCs studied at high resolution, making it an interesting object for potential strong chemical-tagging searches for already dispersed member stars.