Properties of IC 4665 members

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 data sets 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+/-3Myr.