5 papers
WOCS XCIII: NGC 7789: the Evolution of Li, Stellar Rotation, and Extended Main Sequence Turnoffs
Barbara J. Anthony-Twarog, Samantha W. Brunker, Constantine P. Deliyannis +4
Precision UBVRI photometry of NGC 7789 is combined with Gaia data to map reddening variations across the cluster face. HYDRA spectra, Gaia astrometry, and isochrone fitting constra…
Lithium Abundances of Main-Sequence Stars in the Old Open Cluster NGC 188: Probes of Stellar Evolution Beyond the Solar Age
Qinghui Sun, Constantine P. Deliyannis, Bruce A. Twarog +1
We present lithium abundances for 119 main-sequence stars in the old open cluster NGC 188 (age = 6.3 Gyr), using high-resolution, high signal-to-noise ratio spectra from WIYN/Hydra…
Subgiants in NGC 188 Reveal that Rotationally Induced Mixing Creates the Main Sequence Li-Dip
Qinghui Sun, Constantine P. Deliyannis, Barbara J. Anthony-Twarog +3
The "Li-Dip" is an unexpected, striking, and highly non-standard anomaly of severe lithium depletion observed in mid-F dwarf stars, which has puzzled astronomers for nearly 40 year…
C3PO V: Comoving stellar pairs indicate rotational spin-down drives the main-sequence Li-Dip
Qinghui Sun, Yuan-Sen Ting, Barbara J. Anthony-Twarog +4
The lithium-dip observed in mid-F dwarfs remains a long-standing challenge for stellar evolution models. We present high-precision stellar parameters and A(Li) for 22 new comoving…
C3PO III: On the Lithium Signatures Following Planet Engulfment by Stars
Qinghui Sun, Yuan-Sen Ting, Fan Liu +8
Planet engulfment has been identified as one of the mechanisms for enhancing lithium abundance in stars. However, comprehensive investigations into lithium signatures following suc…