2023/09/14 by Jeffries, R. D., Jackson, R. J., Binks, A. S.
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.2309.07619
IC 4665 is one of only a dozen young open clusters with a ``lithium depletion boundary" (LDB) age. Using an astrometrically and spectroscopically filtered sample of cluster members, we show that both the positions of its low mass stars in Gaia absolute colour-magnitude diagrams and the lithium depletion seen among its K- and early M-stars are discordant with the reported LDB age of (32 +4/-5) Myr. Re-analysis of archival spectra suggests that the LDB of IC 4665 has not been detected and that the published LDB age should be interpreted as a lower limit. Empirical comparisons with similar datasets from other young clusters with better-established LDB ages indicate that IC 4665 is bracketed in age by the clusters IC 2602 and IC 2391 at (55 +/- 3) Myr.