A high-resolution spectroscopic study of two new Na- and Al-rich field giants–likely globular cluster escapees in the galactic halo

Abstract

The stars SDSS J0646+4116 and SDSS J1937+5024 are relatively bright stars that were initially observed as a part of the SDSS/MARVELS pre-survey. They were selected, on the basis of their weak CH G bands, along with a total of 60 others, in the range of halo globular cluster (GC) metallicities for high-resolution spectroscopic follow-up as a part of the HESP-GOMPA survey (Hanle Echelle SPectrograph – Galactic survey Of Metal Poor stArs). The stars exhibit typical nucleosynthesis signatures expected from the so-called second-generation stars of GCs. The light-element anticorrelation of Mg–Al is detected, along with elevated abundances of Na. Carbon is found to be depleted, which is compatible with expectation. Lithium is also detected in SDSS J0646+4116 and SDSS J1937+5024; the measured abundances are similar to those of normal halo giant stars. These bright escapees provide a unique opportunity to study the nucleosynthesis events of GC in great detail, and shed light on their chemical-enrichment histories.