Spectroscopic Follow-up of Young High- α Dwarf Star Candidates: Still Likely Genuinely Young

The question of whether genuinely young high- α stars exist has been discussed for more than a decade since their discovery from asteroseismology of giant stars, as it is challenging to break the degeneracy between the binary interaction and the genuinely young scenarios. Young high- α stars are hard to explain with a traditional chemical evolution model, as the high- α disk is typically associated with the early epoch of star formation in the Milky Way. Combined with recent advances of gyrochronology, and that 7 Li can serve as an unambiguous indicator for identifying merger products in dwarfs (thanks to its low burning temperature), we identified young high- α dwarf candidate stars through their fast rotation in a previous study. For this paper, we performed high-resolution spectroscopic follow-up on these candidates using the Potsdam Echelle Polarimetric and Spectroscopic Instrument, and confirm three additional stars that are most likely genuinely young. Together with the star from the earlier paper, we find three out of four of them center around [Fe/H] = −0.5 dex, are ∼5 Gyr old, and have a similar amount of elevated Li (∼0.5 dex) and Al (∼0.1 dex) compared to stars with matching log g , T eff , Mg, and Fe within observational uncertainties, hinting at their common formation pathway.